Deloitte Consulting (including Monitor Deloitte)

Deloitte Case Interview Practice: Free Case and Prep Resources

The Deloitte Case Prep Tool is Deloitte US's free practice site for entry-level consulting candidates: ten cases (seven undergraduate, three advanced degree), 15 to 20 minutes each, and not tracked. Its cases are filed by practice area, from Strategy to Cyber and Valuation, so they feel less like a McKinsey- or Bain-style profitability case and more like the work of the Deloitte team you applied to. Deloitte (opens in a new tab), read

Try a free Deloitte-style case now: Bundt Cake Bakery. No card, no signup.

Free, no signup: 2 worked cases with model answers. Free, no card: your first full Deloitte-style case with an AI interviewer. Paid: Pro $49/month for every case.

Updated By Esteban RonsinFounder · former Deloitte and Accenture Strategy consultant

Built and reviewed with former McKinsey, BCG and Bain consultants and interviewers.

Free Deloitte interview prep resources

Deloitte interview prep resources: what you get, whether it is free or paid, and the link
ResourceWhat you getFree or paidLink
Deloitte case and scenario interview tips
Deloitte's own five-step approach to the case and scenario interview, with links to its free case prep tool for entry-level Consultative Offerings candidates and its scenario tool for Audit & Assurance
Free. Published by Deloitte, checked Nov 9, 2026Open Deloitte's page (opens in a new tab)
Deloitte-style practice cases1 case
1 Deloitte-style case (1 profitability), run out loud with an AI interviewer or step by step and scored on 7 skills; start with Cake or Break
Free + paid. The case list and a worked excerpt are public; a free account includes 1 full AI-graded case in voice or guided mode; Pro ($49/month) adds every caseSee the cases
Halvering Valley Hospital: operations case with answers Industry: Healthcare. Difficulty: hard. 2 math questions.
Why are four times as many patients walking out of a community hospital's emergency department before being seen, and which fix should the hospital fund? 7 questions, 4 exhibits, a model answer for each
Free. The whole case and every model answer, no account; the practice button opens a live case like itRead the case
Corbelworks: pricing case with answers Industry: B2B software. Difficulty: hard. 1 math question.
Should a construction software company price its new scheduling app per seat, per project or in tiers, and at what price? 6 questions, 3 exhibits, a model answer for each
Free. The whole case and every model answer, no account; the practice button opens a live case like itRead the case
Deloitte Immersive Online Assessment guide
What Deloitte UK and Australia say each part covers, the task types, and worked situational ranking and verbal reasoning examples
Free. Every article is publicRead the guide
Deloitte Job Simulation guide
The Job Simulation's ranking, written and video tasks, how it differs from the free Forage simulation, and a worked inbox reply
Free. Every article is publicRead the guide
Deloitte fit interview practice
Deloitte fit and behavioral questions answered out loud, with follow-up probes and structured feedback (choose Deloitte on the page)
Free + paid. 1 behavioral or Learning Mode session with a free account; Behavioral Unlimited ($39/month, behavioral and PEI only) or any Pro plan adds morePractice fit
Deloitte behavioral interview questions
The sample questions Deloitte publishes, the values your stories should show, and worked example answers
Free. Every article is publicRead the guide
Monitor Deloitte case interview guide
The strategy track: the written case, the group case, the individual case and how it differs from Deloitte Consulting
Free. Every article is publicRead the guide
Case Chart Practice Tool
Read an exhibit and state the decision-relevant insight
Free. The rep on the page is free; a free account adds 5 AI-graded drills a day for the first 3 daysTry a rep

Firm-style cases are practice cases written for Road to Offer or adapted from university consulting club casebooks, not the firm's own cases. Road to Offer is independent and not affiliated with Deloitte.

Try a free Deloitte-style case now: no card, no signup

An original practice case written by Road to Offer in a Deloitte-style format, not Deloitte's own case. Everything stays in your browser.

Bundt Cake Bakery: A bundt-cake bakery's falling profit

Written to Deloitte's five steps: understand the issue, state your assumptions, then summarize, recommend and give next steps. The full version is Cake or Break, our library case adapted from the Duke Fuqua consulting club casebook's Deloitte-format case. Deloitte (opens in a new tab), read

Step 1: Read the case

A US bakery chain sells only bundt cakes, in three sizes, in regular flavors plus a rotating pair of seasonal ones. Most sales are to consumers in its stores and online. Profit has fallen since 2020, and the owners ask you why, and how to restore it while still growing.

Step 2: Ask clarifying questions

Open a question to hear the interviewer's answer.

How big is the profit decline?

Interviewer: We don't have a figure, only that profit has fallen since 2020.

Who buys, and through which channels?

Interviewer: Mostly individual consumers, in store and online. Business and catering orders are very small today.

What exactly does it sell?

Interviewer: Five-, ten- and fifteen-inch cakes. In a given month there are six regular flavors and two seasonal ones.

Do we have sales volumes by cake?

Interviewer: No. We have revenue and cost per cake, but not how many of each the chain sells.

What does success look like?

Interviewer: Recover the lost profit and find a practical way to grow. There is no numeric target.

Step 3: Structure your answer

Take two minutes. Lay out how you would find why profit fell and what you would look at to restore it, then say your first hypothesis.

2:00
Show what a strong structure covers
  • Plays the goal back first: restore profit and grow, not only cut costs (Deloitte's step 1).
  • Revenue: customers, cakes per customer, size and flavor mix, and price.
  • Costs: ingredients (seasonal flavors can cost more), labor, rent and equipment.
  • The market: rival bakeries, substitutes and how tastes changed since 2020.
  • Says the assumptions out loud, such as steady store traffic, and which one matters most (step 2).
  • Lists growth options to test later: catering, grocery partners, more seasonal flavors, new cities.
  • Ends with a hypothesis to test first, for example that seasonal cakes earn thinner margins.

Step 4: The interviewer's next question

The interviewer shares unit economics: a five-inch regular cake sells for 6 and costs 4 to make; a five-inch seasonal cake sells for 7.5 and costs 6 (the case gives no currency). Which earns the better margin, and what can you conclude?

Show what a strong answer does

Regular keeps a third of its price (2 on 6), seasonal a fifth (1.5 on 7.5), so seasonal cakes bring more revenue per cake but less margin. Without volumes you cannot say which line drives total profit, so a strong answer asks for the sales mix before recommending anything.

Now run the full case, Cake or Break, out loud with the AI interviewer

A Deloitte voice case in 3 steps

A Voice case call: Alex, the AI interviewer, on camera, the live transcript beside him, and the mic to answer.
  1. Choose a case

    Cases matched to Deloitte's case types.

  2. Solve it out loud

    An AI interviewer asks, listens and follows up.

  3. Get answer feedback

    Feedback on every answer: what worked, what to fix.

What makes Deloitte interviews different

Key facts from Deloitte's own pages

The Deloitte Case Prep Tool, case by case

Every case in Deloitte US's Case Prep Tool with the level and practice area Deloitte gives it, plus the Scenario Prep Tool for Audit & Assurance. Each line is our summary of the case's own business situation. Read on Deloitte's site .

The Deloitte Case Prep Tool, case by case: level, area and what each one is, linked to Deloitte's page
ResourceLevelAreaWhat it is
Deloitte Case Prep Tool (opens in a new tab)Entry levelConsultative OfferingsThe practice site: ten cases, each a business situation, a problem statement and questions with a suggested answer to check your work. Not tracked.
Recreation Unlimited (opens in a new tab)UndergraduateFunctional and Operations Strategy, Enterprise StrategyA global sportswear brand lags rivals online and wants fast direct-to-consumer digital growth, plus the talent and organization changes it needs. Worked below.
XFintech Inc. Ransomware Attack (opens in a new tab)UndergraduateCyberRansomware has encrypted a mid-sized fintech's critical systems and data after an employee opened a malicious attachment; the CTO wants immediate advice.
Data Exfiltration (opens in a new tab)UndergraduateForensicA fired executive is accused of taking digital intellectual property; you plan a forensic investigation on encrypted company devices, from collection to analysis.
Applied AI, Automation, and the Future of Work (opens in a new tab)UndergraduateForensic AnalyticsA large financial institution with scattered AI and automation pilots needs one roadmap for adopting them across the organization.
Architecture Strategy: Federal Finance Agency (opens in a new tab)UndergraduateTech Transformation, Enterprise Tech StrategyA sanctions division with siloed legacy systems, high turnover and a paperwork backlog wants one shared enterprise architecture and a plan to implement it.
Show all 12
The Deloitte Case Prep Tool, case by case, continued
ResourceLevelAreaWhat it is
Construction Delays: Project Analysis (opens in a new tab)UndergraduateValuationA general contractor is behind schedule after weather and supply chain delays and worries about cost overruns and delay penalties from the owner.
Industrial Warehouse Valuation (opens in a new tab)UndergraduateValuationA Midwest property owner needs an opinion of value for a single-tenant industrial warehouse off Interstate 90 whose lease runs to 2031.
Finance Strategy: Federal Health Agency (opens in a new tab)Advanced degreeStrategyA federal health agency fighting the 2014 Ebola epidemic must track emergency funds by program and flag programs behind plan before a monthly report to Congress.
LeadAuto: Market Expansion (opens in a new tab)Advanced degreeStrategyAsia's leading automaker expects slow growth and weighs entering the bus market, with two product configurations and unclear profit per bus.
Talent Management: Federal Civil Cargo Protection Bureau (opens in a new tab)Advanced degreeStrategyA cargo security agency hit by screening lapses and falling morale needs a review of screening and hiring and a human capital strategy.
Deloitte Scenario Prep Tool (opens in a new tab)Entry levelAudit & AssuranceThe scenario interview's practice site in the same format: eleven scenarios in nine areas, from Business Process Controls Advisory to Valuation & Analytics.

Worked: Recreation Unlimited, in Deloitte's five steps

A UK-founded global sportswear brand sells 5% of its goods online against an industry average of 10%, and asks Deloitte to grow its direct-to-consumer digital sales by 40% a year for five years, with the talent and organization changes that takes. Deloitte's tool asks five questions: why it lags online, how to improve the digital experience, a better website or more digital ads, the value of a website upgrade, and the people implications. Read the official case (opens in a new tab) (read )

How you might work it is ours, not Deloitte's answer key.

  1. Understand the issue

    Play the goal back: grow online direct sales 40% a year, and change the organization so the growth holds. Then ask what growth is measured on (revenue or profit), which regions come first (Europe is its biggest market; Latin America, Asia-Pacific and Africa are growing) and what budget exists, since the case later forces a choice.

  2. Identify the underlying assumptions

    Say what the target rests on: shoppers want to buy this brand online, the gap to the industry average is the prize, and stores and online can grow together. Name the one that would change the plan most if wrong: if shoppers choose rivals' sites on price, a better website alone will not close the gap.

  3. Summarize issues and findings

    Group the reasons it lags into internal (no digital plan, a very hierarchical organization, training cut, turnover among younger staff) and external (shoppers moving online, rivals ahead). For the website question the math is quick: 20 million visitors spending one dollar more at a 50% margin is 10 million a year of profit, so a ten-million-dollar one-time cost pays back in about a year.

  4. State recommendations

    One answer: fund the website first, because it pays back in about a year and makes later ad spend convert better, then add targeted digital ads in the growth markets. Say what would change it: if visitors do not spend more after the upgrade, the payback stretches and ads may win.

  5. Outline next steps and expected impact

    Who does what in the first 90 days: a digital lead with authority across the hierarchy, a website pilot in one market, training restored for digital and store teams. Expected impact: the online share moving toward the industry average, tracked monthly, and lower turnover among younger staff.

Method: Deloitte (opens in a new tab), read

What Deloitte looks for, in its own words

Logic over the right answer

Deloitte US says you are not expected to provide the “right” answer, but to clearly convey your logic and thought process. Source: Deloitte, read (opens in a new tab)

Clear thinking, practical judgment, professional demeanor

Those are the three things Deloitte says it looks for in case and scenario answers, and it wants to see how you “connect the dots”. Source: Deloitte, read (opens in a new tab)

Questions, but not as a crutch

Ask clarifying questions, Deloitte’s tips say, but “don’t use them as a crutch”. Take notes, take time to compose your thoughts, and share a framework and an initial hypothesis. Source: Deloitte, read (opens in a new tab)

More expected as you get senior

Deloitte Australia asks Analyst and Consultant candidates to apply basic business concepts such as revenue, profit, market share, customers, competitors and stakeholders, and from Senior Analyst or Senior Consultant up to suggest the data that would prove or disprove a hypothesis. Source: Deloitte, read (opens in a new tab)

A conversation with a client

Deloitte New Zealand says verbal case interviews are meant to be conversational, and to interact with your interviewer or panel as you would with a client. Source: Deloitte, read (opens in a new tab)

The Deloitte interview process, and what trains each step

  1. Online assessment, where your country uses one

    Deloitte UK's early careers process starts with the Immersive Online Assessment: a behavioural part where you rank actions in workplace scenarios, and a cognitive part with numerical and verbal reasoning. There is no overall time limit, some sections are timed, and Deloitte links free practice in its Candidate Zone. Deloitte's US recruiting tips name no online assessment.

    Source: Deloitte careers (opens in a new tab), checked

    Train it with:

  2. Job Simulation

    In the UK the next stage asks you to rank and select responses, write answers and record video answers. Some scenarios mention AI tools, but Deloitte says you need no prior AI experience.

    Source: Deloitte careers (opens in a new tab), checked

    Train it with:

  3. Two to three interview rounds

    Deloitte US says to expect two to three rounds of interviews by telephone, video or in person, with a mix of behavioral, technical and case-based interviews depending on the role.

    Source: Deloitte careers (opens in a new tab), checked

    Train it with:

  4. Behavioral interview

    Deloitte publishes sample questions on juggling responsibilities, taking the initiative to fix a problem, a conflict with a team member and a rush project with missing information, and recommends structuring answers as situation, task, action, result.

    Source: Deloitte careers (opens in a new tab), checked

    Train it with:

  5. Case or scenario interview

    Fictional cases that reflect real client work. Deloitte's five steps: understand the issue, identify the underlying assumptions, summarize key issues and findings, state recommendations, and outline next steps and expected impact. Deloitte says the goal is to explain your reasoning, not to reach one right answer.

    Source: Deloitte careers (opens in a new tab), checked

    Train it with:

  6. Final stage assessment (UK)

    A two-way topic discussion of about 30 to 40 minutes, based on research you prepare beforehand, and a skills and motivation interview of about 50 minutes. Summer Vacation Scheme candidates do the interview only, virtually.

    Source: Deloitte careers (opens in a new tab), checked

    Train it with:

  7. Monitor Deloitte interviews

    Monitor Deloitte Sweden describes four personal interviews over two days, with a written case and several oral cases, plus a reasoning test and a personality test. The page also mentions a 2018 boot camp, so confirm the current format with your recruiter.

    Source: Deloitte careers (opens in a new tab), checked

    Train it with:

Rounds, timing and what each interview covers in depth: Deloitte Case Interview: Format, Questions and Prep.

Missing from Deloitte's pages: how long a live US case interview runs, whether it is interviewer-led or candidate-led, how answers are scored, and whether the US uses an online assessment before the interviews.

13 Deloitte-style interview questions

In our words, not Deloitte's, grouped by Deloitte's five steps, with what a strong answer does. Several share a theme with an official case (a federal program's funds, a brand selling online, a public asset); work ours, then Deloitte's own case in the table above.

Step 1: Understand the issue

Deloitte: ask clarifying questions, but don't use them as a crutch.

  1. A state transit agency's ridership is still a fifth below where it was five years ago. The director asks how to bring riders back. What do you clarify before you structure anything?

    What a strong answer does: Asks the two or three questions that would change the plan (which riders left, on which routes, what budget and who decides), states a first hypothesis, then stops asking.

    Practice it:Case Structure Practice Tool

  2. A regional bank's online account openings stall halfway through the application. What do you need to know first?

    What a strong answer does: Separates where people drop (which screen, which device) from why (identity checks, time, trust), and asks what the bank counts as success before proposing fixes.

    Practice it:Issue Tree Examples

  3. A packaged-food maker's new plant-based line sells well in stores but loses money. What problem do you play back?

    What a strong answer does: Restates the goal as profit, not sales, names where profit can leak (price and mix, cost to make and to move), and checks the time frame.

    Practice it:GreenBite Snacks Profitability Reset

Step 2: Identify the underlying assumptions

Deloitte asks you to recognize and articulate the assumptions behind a case.

  1. How many public electric vehicle chargers does a mid-sized US city need by 2030?

    What a strong answer does: Builds from vehicles, the share that are electric, charges per week and charges per charger, says each assumption out loud and names the one that swings the answer most.

    Practice it:Market Sizing Practice Tool

  2. A sportswear brand's online plan assumes shoppers will pay full price. How would you test that before building on it?

    What a strong answer does: Names the evidence that would prove or disprove it (share of online sales at a discount, returns, rivals' prices) and the fastest test, such as a price trial in one market.

    Practice it:Case Brainstorming Practice Tool

Step 3: Summarize issues and findings

Deloitte: summarize specific issues and findings, as a clear, logical story.

  1. A federal grant program has spent only 60% of its budget with two months left. You have spending by region. What is your summary?

    What a strong answer does: Leads with the finding (where the underspend sits and why it matters to the funder), then the regions behind it, then what you would check next.

    Practice it:Case Synthesis Practice Tool

  2. An exhibit shows a retailer's online sales up 30% while store sales fell 8%. What do you say first?

    What a strong answer does: Reads the units and time frame, states the effect on total sales before the details, and asks for the number that settles it: the online share of the total.

    Practice it:Case Chart Practice Tool

  3. A manufacturer's warehouse costs rose 18% in a year while volumes stayed flat. Walk me through your math.

    What a strong answer does: Splits cost into rate and quantity (labor hours, space, days in storage), computes which one grew, and says the finding in one sentence before the arithmetic.

    Practice it:Case Math Practice Tool

Steps 4 and 5: Recommend, then next steps and impact

Deloitte's last two steps: state your recommendations, then outline next steps and expected results.

  1. A mid-sized insurer can afford either a new claims system or more claims staff this year. What do you recommend?

    What a strong answer does: Picks one with the number that decides it (cost per claim, backlog cleared), names the main risk, and ends with the first three moves and how impact will be measured.

    Practice it:Deloitte-style practice cases

  2. A city is offered a long-term deal to hand its public bike share to a private operator. Should it accept?

    What a strong answer does: Weighs the payment against the income and control over prices the city gives up, lands on yes or no with conditions, and says the next step.

    Practice it:City Bike Share Concession

  3. A logistics company bought a software startup a year ago and the two teams still work apart. What do you recommend for the next 90 days?

    What a strong answer does: Gives one integration priority with a reason (shared customers, one roadmap or one sales team), then owners, milestones and the metric that shows it worked.

    Practice it:NorthStar Logistics Acquisition of RouteWave TMS

Behavioral, in STAR

Deloitte US recommends the STAR method, and a short elevator pitch for “Tell me about yourself”.

  1. Tell me about a time you changed a plan because the data told you to.

    What a strong answer does: Keeps the situation short, then the data you saw, the call you made and a result in numbers: it shows the practical judgment Deloitte names, not only effort.

    Practice it:Deloitte fit interview practice

  2. Why Deloitte, and why this practice area?

    What a strong answer does: Names the practice and one kind of work it does (an official case from that area helps), links it to something you have done, and stays under a minute.

    Practice it:Deloitte behavioral interview questions

Easy ways to lose a Deloitte interview

Stopping at the recommendation

Deloitte's fifth step is next steps and expected results. End every case with who does what next and how you will know it worked. Source: Deloitte, read (opens in a new tab)

Asking until time runs out

Deloitte's tips say to ask questions but not to use them as a crutch: it wants to see you connect the dots. Source: Deloitte, read (opens in a new tab)

Treating the interviewer as an examiner

Deloitte asks you to engage the interviewer in a business conversation, as with a client. Long silent note-taking reads as the opposite. Source: Deloitte, read (opens in a new tab)

Preparing for the wrong interview

In the US, entry-level Audit & Assurance candidates get a scenario interview, not a case. Check which one your invitation names and use the matching Deloitte tool. Source: Deloitte, read (opens in a new tab)

Practicing only out loud

Deloitte New Zealand says a case may be answered verbally, in writing or both. Write one half-page case answer before the interview. Source: Deloitte, read (opens in a new tab)

A Deloitte prep plan, day by day

The order follows Deloitte's own pages; the timing is our suggestion.

  1. Days 1 and 2

    Read Deloitte's own guidance

    Read the case and scenario tips and the five steps, and check from your invitation whether you face a case or a scenario interview.

  2. Days 3 to 5

    Work the Case Prep Tool at your level

    Do the cases for your level, starting with your practice area. Write each answer down before you open Deloitte's suggested answer, since the tool keeps nothing.

  3. Days 6 to 9

    Run cases out loud

    Run a Deloitte-style case with an AI interviewer and check you reached all five steps, next steps and impact included. Add a chart rep each day.

  4. Days 10 and 11

    Write one case up

    Answer one official case in half a page: the finding, the recommendation, next steps and expected impact, for offices that take written answers.

  5. Days 12 and 13

    Prepare your behavioral stories

    Write an elevator pitch for “Tell me about yourself” and a STAR story for each of Deloitte's published sample questions, then say them out loud.

  6. Day 14

    One full mock, then rest

    One full case and two behavioral questions under time, then review only what you missed.

A week-by-week schedule built around Deloitte and your interview date.

Get a Deloitte prep plan

Deloitte interview prep questions

How should I prepare for the Deloitte case interview, and which free resources should I use?

Start with Deloitte's own case and scenario interview tips and the free case prep tool it links for entry-level Consultative Offerings candidates, then train each step your invitation names: an online assessment where your country uses one, the behavioral interview and the case interview. Deloitte US says to expect two to three rounds mixing behavioral, technical and case-based interviews. On Road to Offer a free account includes 1 full AI-graded case, such as Cake or Break, our Deloitte-style profitability case; Halvering Valley Hospital and Corbelworks are worked cases with a model answer for every question and need no account. Firm-style cases are practice cases written for Road to Offer or adapted from university consulting club casebooks, not the firm's own cases.

Where can I practice Deloitte-style case interviews for free?

Deloitte's own free case prep tool, linked from its case and scenario interview tips page, is the first place. On Road to Offer, Cake or Break is a Deloitte-style profitability case you run out loud with an AI interviewer or step by step; your first full case is free with a free account. Halvering Valley Hospital (operations) and Corbelworks (B2B software pricing) are free to read with a model answer for every question, no account. They are written in other firms' styles and picked because many of Deloitte's published practice case titles name government, health or technology clients.

Does Deloitte have an online assessment before the interviews?

It depends on the country. Deloitte UK's early careers process has the Immersive Online Assessment (ranking actions in workplace scenarios, plus numerical and verbal reasoning), then a Job Simulation with ranking, written and recorded video answers. Deloitte Australia uses the Immersive Online Assessment, then a digital interview or, for some roles, a Job Simulation. Deloitte's US recruiting tips name no online assessment. Road to Offer has no Deloitte assessment simulator: our Immersive and Job Simulation guides walk through worked examples, and Deloitte UK links free official practice in its Candidate Zone.

What behavioral interview questions does Deloitte ask consulting candidates?

Deloitte US publishes sample questions about juggling a lot of responsibilities, seeing a problem and taking the initiative to correct it, a conflict with a team member, and a rush project without all the information you needed, plus leading a project or team and adapting to a significant change. It recommends structuring answers as situation, task, action, result. Prepare one story for each and say it out loud; Road to Offer's fit practice asks Deloitte questions with follow-up probes, 1 session free with a free account.

How is the Monitor Deloitte interview different?

Monitor Deloitte is Deloitte's strategy practice, and its Swedish careers page describes four personal interviews over two days with a written case and several oral cases, plus a reasoning test and a personality test. That page also mentions a 2018 boot camp, so confirm the current format with your recruiter. Our Monitor Deloitte guide covers the written case and the group case candidates report.

What is the Deloitte Case Prep Tool?

Deloitte US's free practice site for entry-level Consultative Offerings candidates: ten cases, seven for undergraduates and three for advanced degree students. Each case is a real-life business situation and problem statement with a series of questions; you answer, then check a suggested answer. Deloitte estimates 15 to 20 minutes a case. It sits at usrecruiting.deloitte.com, linked from Deloitte's case and scenario interview tips.

Does Deloitte see my answers in the Case Prep Tool?

No. Deloitte says the tool is not an assessment and it does not track your responses or results. Your answers are not saved and cannot be retrieved after you submit, so write them down if you want to review them, and practice as often as you like.

Which Deloitte practice case should I do first?

One at your level, in the practice area closest to the team you applied to. The three advanced degree cases are all filed under Strategy (a federal health agency, LeadAuto and a cargo security bureau); the seven undergraduate cases span strategy, cyber, forensic, forensic analytics, tech transformation and valuation.

Is there a Deloitte prep tool for Audit & Assurance candidates?

Yes. In the US, entry-level Audit & Assurance candidates get a scenario interview instead of a case, and Deloitte's Scenario Prep Tool has eleven practice scenarios in nine areas, in the same format as the Case Prep Tool.

Is the Deloitte case interview written or spoken?

It can be both. Deloitte US asks you to engage the interviewer in a business conversation, and Deloitte Australia and New Zealand say a case may be resolved verbally, in writing or both, so practice a short written answer as well as a spoken one.

Is the Deloitte case interview interviewer-led or candidate-led?

Deloitte's pages don't say. Its tips ask you to develop a framework and an initial hypothesis and walk the interviewer through your thinking, which works in either format. The Case Prep Tool itself asks a fixed series of questions, closer to an interviewer-led case.

How soon does Deloitte make an offer?

Deloitte US says that if you are selected, a recruiter usually contacts you within one to two weeks to schedule a first interview, and that if you receive an offer you will likely have it in writing within one week of your final interview.