Deloitte case interview: 4 practice cases with worked examples (2026)

The Deloitte case interview is usually a live, interviewer-led business problem of 20 to 40 minutes with a practical flavour: find what is really going wrong, size it, then say how you would fix it and who would do what. It typically sits alongside competency questions, in the same interview or a separate one. Processes vary more than at McKinsey, BCG or Bain: by country, by service line, and between Deloitte's consulting teams and its strategy arm, Monitor Deloitte. Some offices use a written case or a group case, especially at assessment centres, and many add online tests. Your invitation is the best guide.

Interviewer-led means the interviewer sets the questions and hands you data as the case moves on. You still need a structure, but the job is to answer each question cleanly and say what it means for the client. The last questions are often about delivery: how would you implement this, who needs to be on board, what could go wrong. Candidates who stop at the analysis leave marks on the table.

Two cases in our library are written in the Deloitte style. We add two operations cases written in other firms' styles (McKinsey and Kearney) because they test exactly what Deloitte operations and public sector interviews probe: capacity, cost and a plan that works on the ground. All four are interviewer-led and have guided walkthroughs.

Start with Calder: the maths is a single capacity equation and the case rewards a clear implementation plan. Leave Hartwell until last, because it asks you to net several moving parts against a headline number.

The core method is the same: clarify, structure, analyse, recommend. The differences are in format and emphasis. Monitor Deloitte is commonly reported to run cases close to the MBB style; elsewhere the case tends to feel more like a practical business discussion. Treat the table as tendencies, not rules; our MBB vs Big 4 guide covers the wider differences.

Calder Benefits Agency clears its backlog

The prompt. The Calder Benefits Agency processes about 30,000 applications a month for a housing support benefit. Applicants wait more than six weeks for a decision against a four-week target, the backlog has more than doubled in a year, and the director wants to hire 40 more caseworkers. How would you cut the backlog and the cost per application? Ask about capacity and constraints: 250 caseworkers with about 112 productive hours a month each, and a legal duty to keep accepting paper.

A fitting structure. Write the capacity equation first: demand (applications × handling time) against capacity (caseworkers × productive hours). Break handling time down by channel and by process step, including rework on incomplete applications. List levers beyond headcount (channel shift, form redesign, triage, a temporary surge team), then implementation.

The calculations. Check the average: 60% × 75 + 20% × 50 + 20% × 25 = 45 + 10 + 5 = 60 minutes. A paper application takes three times as long as an online one. Every 10 points of applications moved from paper to online cuts the average by 0.1 × (75 - 25) = 5 minutes and saves 0.1 × ($90 - $30) = $6 per application, about $2.2m a year on 360,000 applications.

DeloitteCalder Benefits Agency clears its backlogOperations · Easy

Calder Benefits Agency clears its backlog

Finish it: the capacity gap, the backlog trend, where a paper application's time goes and the plan you would put to the director.

Interviewer

Our client is the Calder Benefits Agency, which processes about 30,000 applications a month for a housing support benefit. Applicants now wait more than six weeks for a decision against a four-week target, and the backlog has more than doubled in a year. The director wants to hire 40 more caseworkers. How would you help the agency cut the backlog and its cost per application?

Start the caseGuided, step by step

Vantage Retail's warehouse bottleneck

The prompt. Vantage Retail runs a single distribution centre serving 180 stores. It misses delivery windows on about 12% of store orders and is considering a £40m second facility. Is that the right move? Ask where the failure shows up: a vehicle that leaves on time arrives on time 99% of the time, so the problem is inside the building.

A fitting structure. Map the flow end to end (inbound receipt, putaway, picking, loading, transport), compare capacity with demand at each stage, and find the binding constraint before judging any fix. Then compare options on cost, time and risk, with the £40m building as the baseline.

The calculations. Utilisation of the pallet stages: inbound 3,100 ÷ 5,000 = 62%, putaway 3,100 ÷ 4,600 ≈ 67%, picking 3,100 ÷ 4,200 ≈ 74%. Every one has at least a quarter of its capacity spare. Each vehicle carries 3,100 ÷ 135 ≈ 23 pallets.

DeloitteVantage Retail's warehouse bottleneckOperations · Medium

Vantage Retail's warehouse bottleneck

Finish it: when the misses happen, dock capacity, why near-full capacity fails, and the cheapest fix.

Interviewer

Vantage Retail runs a single distribution centre serving 180 stores. They are missing delivery windows on about 12% of store orders and are considering a GBP 40m second facility. Is that the right move?

Start the caseGuided, step by step

These two are written in McKinsey and Kearney styles, but both are the operations problems Deloitte's public sector and supply chain teams are hired for.

Kingsmere Hospitals cuts its surgery waiting list

The prompt. Kingsmere Hospitals, a public trust running two acute hospitals, has seen its planned surgery waiting list grow from about 6,700 to 9,600 patients in three years. The board is about to approve GBP 9m for two new operating theatres, and the chief executive wants to know what is really limiting surgery. Ask about the goal: the list back to about 5,600 within three years. The board's paper says two new theatres add about 2,400 operations a year.

A fitting structure. Follow the patient pathway: demand, theatre capacity (sessions × operations a session), beds after surgery, staff. Put every stage in one unit, operations a year, then test the new theatres against cheaper ways to release capacity.

The calculations. The list grows by additions minus operations: in 2025, 13,400 - 12,000 = 1,400, exactly the rise from 8,200 to 9,600. Both sides moved: additions are up 8% since 2022 and operations down about 5%. To cut the list by 4,000 in three years with demand flat, Kingsmere needs about 13,400 + 1,333 ≈ 14,700 operations a year, about 2,700 (23%) more than in 2025.

McKinseyKingsmere Hospitals cuts its surgery waiting listOperations · Medium

Kingsmere Hospitals cuts its surgery waiting list

Finish it: theatre time, cancellations on the day, bed capacity and the plan for the board.

Interviewer

Our client is Kingsmere Hospitals, a public hospital trust running two acute hospitals. Its waiting list for planned surgery has grown from about 6,700 to 9,600 patients in three years, and the board is about to approve GBP 9m for two new operating theatres. The chief executive has asked us to find out what is really limiting surgical activity and what it would take to fix it. How would you approach this?

Start the caseGuided, step by step

Hartwell Grocers redraws its distribution network

The prompt. Hartwell Grocers runs 320 supermarkets from four regional distribution centres. The operations director wants to close the North and South-West DCs, expand the other two, and says it will save $24m a year. Should the CEO approve it? Ask about the rules: payback within four years, fresh on shelf before 6am, and 98% of deliveries on time.

A fitting structure. Test the headline line by line: warehouse cost (fixed cost removed, variable cost that moves, expansion), transport (longer trips), one-off costs, then service and fresh waste. Payback against four years, closure by closure.

The calculations. North and South-West handle 110m of the 300m cases (37%) but carry $30m of the $57m fixed cost (53%), which is why their cost per case is about $0.48 against $0.34. Closing them removes at most that $30m of fixed cost. The $22m of variable cost (110m cases × $0.20) moves with the cases and is not saved.

KearneyHartwell Grocers redraws its distribution networkOperations · Hard

Hartwell Grocers redraws its distribution network

Hard. Finish it: transport cost, payback, closure by closure, and what drive time does to fresh waste.

Interviewer

Our client, Hartwell Grocers, runs 320 supermarkets served from four regional distribution centres. The operations director wants to close the North and South-West DCs, expand the other two, and says the move will save $24m a year. The CEO wants to know whether to approve it. How would you approach the decision?

Start the caseGuided, step by step

Some Deloitte offices replace or add to the live case with a written or group exercise, most often in graduate assessment centres and final rounds. Formats differ widely, so ask the recruiter how long you have, whether you present, and whether a calculator is allowed.

The group case. A small group of candidates gets the same brief and discusses it for a set time while assessors watch, often finishing with a short presentation. Assessors are commonly reported to watch how you work with others as much as what you conclude: whether you build on ideas, bring in quieter people, keep the group to time and pull the discussion together.

The written case. You get a pack of data and slides, time alone to analyse it, then present your recommendation, sometimes on slides you build, followed by questions. The skill is prioritisation: most packs hold more data than you need. Read the question first, find the two or three exhibits that answer it, and build the answer before the slides.

• Can you write a capacity equation (demand in hours against hours available) within a minute of hearing an operations prompt?
• Do you find the bottleneck before you judge a fix, and convert every stage into the same unit?
• Can you separate fixed from variable cost, and say what a closure or volume change really saves?
• Does every recommendation you give end with an owner, a sequence, a measure and the main risk?
• Have you practised a written case alone and timed, and contributed to a group discussion without taking it over?
• Do you have 6 to 8 competency stories with a clear situation, your action and a measurable result? Our fit interview lesson shows how to build them.

1. Start with Calder: redo the first exhibit's maths yourself, then run the case guided.
2. Run Vantage and Kingsmere live with the AI interviewer, out loud and timed at about 30 minutes.
3. Take Hartwell as a written case: 30 minutes alone with the exhibits, a one-page answer, then a three-minute presentation.
4. After each case, check yourself against the list above and drill the weakest skill. Close every case with an implementation plan, even when nobody asks for one.