Assessors do not score how many exhibits you opened. They score whether the first slide states a decision a partner can act on, with two or three evidence-backed reasons and one named risk. That is the thesis of every written case I have sat on the other side of: BCG and Bain final-round packs, Strategy& slide packs, and Big Four assessment-centre write-ups all collapse to the same product.
This guide stays on the individual written case. Group exercises and inbox drills belong in a separate playbook. After you finish, you should be able to run a timed pack, build a four-slide skeleton, and defend one recommendation without rewriting the deck mid-presentation.
What firms publish about the format
Firms describe the skill, not a universal timetable. Use their own language, then confirm your invitation.
| Firm / route | What the firm states publicly | What that means for you |
|---|---|---|
| BCG case interviews | Work a realistic business challenge: structure, analyze data, calculate, identify the important factors; communicate clearly; there is not always a single right answer | Your deck must show prioritization and reasoning quality, not exhibit coverage |
| Bain interviewing | Consulting roles use case interviews; some roles include a take-home written assignment (often about three days) and may require a presentation | If your invite names a written deliverable, treat packaging and defense as part of the score |
| Strategy& UK | Structured case with a slide pack reflecting a real client project; about 10 minutes to review before developing recommended solutions; judges how you structure an approach, not the one right answer | Short prep windows reward triage: question first, then the three exhibits that answer it |
| Deloitte UK professional assessment | Assessment centres assess several people at once; tools can include case studies on the spot or presented back, plus tasks completed beforehand or during the interview | Expect a written or presentation output; the invitation names the exact mechanic |
BCG's careers page is blunt: quality of reasoning beats a magic answer. Strategy& UK is equally blunt: the structured pack tests how you structure an approach. Bain's interviewing page separates consulting cases from role-specific written assignments. Deloitte lists assessment centres and case studies that may be presented back. None of those pages publish a confidential scoring sheet. Treat "two hours and five slides" folklore as something to verify with your recruiter, not as a firm-wide rule.
How I score the deck from the other side of the table
When I read a written case, I spend the first thirty seconds on slide one only. If I cannot restate your recommendation, the supporting reasons, and the next operational step without flipping forward, the rest of the pack is already fighting uphill.
I listen for four things:
- Decision clarity. Enter / do not enter. Cut price / hold / raise. Acquire A / walk away. Soft language ("consider exploring options") loses points even when the analysis is fine.
- Evidence that moves the decision. One chart or one calculation per reason. Decorative industry color does not count.
- Explicit assumptions. Bain's own case-prep guidance tells candidates to clarify the objective and structure thinking; on paper, that shows up as labeled hypotheses, not buried footnotes.
- A falsifier. The one fact that would reverse you. Partners trust candidates who name what would change their mind.
What leaks points in a typical room of eight: three candidates bury the answer on slide four; two spend the clock polishing bar charts that never appear in the recommendation; one calculates correctly and still never states what the client should do on Monday.
Ned's rule. Write the slide title as a sentence the CEO could approve or reject. If the title is a topic ("Market overview"), the slide is not ready.
A minute-by-minute plan for 60–90 minutes
Use this clock whether your pack is a timed assessment-centre write-up or a final-round prep block. Scale the middle band if you have 90 minutes instead of 60.
| Clock | Minutes | Job |
|---|---|---|
| 0–5 | 5 | Read the ask twice. Write the decision question in one line. List any stated sub-questions. Do not open exhibits yet. |
| 5–15 | 10 | Skim every page once. Tag each exhibit: must-use, maybe, noise. Cap "must-use" at four. |
| 15–35 | 20 | Run only the analyses that answer the decision question. One primary calculation. Note units and source labels. |
| 35–45 | 10 | Commit. Draft the recommendation sentence, three reasons, one risk, one next step. |
| 45–55 | 10 | Build the deck from the skeleton below. Titles first; charts second. |
| 55–60 | 5 | Stress-test: what would reverse you; which exhibit you will point to in Q&A; arithmetic check. |
| (If 90) 60–75 | 15 | Add one deeper exhibit or sensitivity; still do not add a fifth "nice to know" slide. |
| (If 90) 75–90 | 15 | Rehearse the 8–12 minute oral: decision, reasons, risk, ask. |
Two traps: reading the pack cover to cover before writing the question, and building slides before the recommendation sentence exists. Both burn the only resource that matters in a written case: prioritization under time.
The slide skeleton I want on the table
Four slides. Five only if the brief demands a separate appendix. Action titles, not section labels.
Slide 1 — Recommendation. Title: the decision in one sentence. Body: three bullets, each a reason. Footer: one next step and owner ("Pilot price rise in Segment B next quarter; measure volume elasticity at week 4").
Slide 2 — Why the numbers support it. Title: the quantitative punchline ("Segment B contributes 62% of profit on 28% of volume"). One chart or table. Source note. No dual-axis art.
Slide 3 — Strategic or operational logic. Title: the non-math reason ("Competitors cannot match service density in the North for 18 months"). Two bullets of evidence from the pack. One assumption labeled as such.
Slide 4 — Risk and what would reverse us. Title: the falsifier ("If Segment B churn exceeds 8%, hold price"). Mitigation in one line. Optional: open question for the interviewer, phrased as a trade-off, not a request for the answer.
Strategy&'s public UK process already trains this muscle in a compressed form: ten minutes with a client-style pack, then recommended solutions. The longer BCG- or assessment-centre-style windows only buy you more room to make the same four slides cleaner, not the right to write a literature review.
Worked example: Harborline Regional Rail (75 minutes)
Original case. Invented figures. Reproduce the math yourself.
Ask. Harborline runs three regional routes. Management asks whether to raise peak fares 12% on the Coast route next year to fund rolling-stock upgrades. Produce a short recommendation deck.
Exhibits (summarized). Coast peak load factor 91%; Inland 64%; Hills 58%. Coast peak contribution margin $18 per passenger; Inland $9; Hills $7. Elasticity study: Coast peak fare elasticity estimated at −0.4; Inland −0.9. Competitor coach fares on Coast corridor are 22% below Harborline peak. Upgrade CAPEX $42M; required incremental annual contribution to clear hurdle: $6.5M. Coast peak annual passengers: 4.2M.
Decision question (minute 3). Should Harborline raise Coast peak fares 12% now, and will the economics clear the $6.5M hurdle after volume loss?
Math (minutes 18–32).
- Current Coast peak contribution: 4.2M × $18 = $75.6M.
- Price up 12%. Expected volume change ≈ −0.4 × 12% = −4.8%. New volume ≈ 4.0M.
- New contribution per passenger ≈ $18 × 1.12 = $20.16 (holding variable cost constant — labeled assumption).
- New contribution ≈ 4.0M × $20.16 = $80.6M.
- Incremental contribution ≈ $5.0M — short of the $6.5M hurdle by about $1.5M.
Recommendation (slide titles).
- Do not raise Coast peak fares 12% alone; it clears only ~$5.0M of the $6.5M hurdle. Pair a smaller Coast rise with an Inland off-peak yield program, or stage CAPEX.
- Coast already runs at 91% load; a blunt 12% rise trades scarce peak seats for incomplete funding. Show the $75.6M → $80.6M bridge and the −4.8% volume haircut.
- Coach undercuts Coast peak by 22%; elasticity −0.4 is a mid-case, not a floor. If true elasticity is −0.6, incremental contribution falls to roughly $2.7M — still short, and worse.
- Reverse the call if a phased 6% rise plus $2M of non-fare contribution (advertising, parcels) is locked before CAPEX approval. Next step: 90-day pilot at +6% on two Coast peak trains; measure load and complaint rate weekly.
That deck is scorable in thirty seconds. A candidate who instead builds six slides on tourism trends, historical rail regulation, and a SWOT of "mobility" will usually lose to this one even if their arithmetic is identical.
Practice this under a clock
Tonight: pick any multi-exhibit pack from a school case book or from CoachNed's case library. Give yourself 60 minutes. Produce only the four-slide skeleton above. Then present aloud for ten minutes to a phone recording. Score yourself with one question: could a partner act on slide one without flipping?
For the synthesis muscle the written case rewards — recommendation first, evidence second — run a free synthesis drill, then a full timed case once you want a live debrief.
Everything on CoachNed is open for seven days, no card; then $120 for a recruiting season or $49 a month. The five-minute start path works without an account if you only need a first typed rep. The voice interview is the right next step when your written pack is solid but the oral defense still wobbles.
If your invitation is a group case or an inbox exercise rather than an individual write-up, switch to the group case and inbox playbook instead of stretching this one.
CoachNed is not affiliated with McKinsey, BCG, Bain, Deloitte, PwC, Strategy&, or any firm named here.
Frequently asked questions
How long is a consulting written case interview?
Public firm pages rarely publish one global clock. Strategy& UK describes about ten minutes with a structured slide pack before recommending solutions; Bain notes some non-consulting written assignments may allow roughly three days; assessment-centre write-ups often sit in a 60–90 minute window. Confirm the number on your invitation.
What should I put on the first slide of a written case?
The decision in one sentence, three supporting reasons, and one next step. Assessors read that slide first. Topics, agendas, and "executive summaries" that delay the call waste the only page that always gets full attention.
How is a written case different from a live case interview?
In a live case the interviewer paces you. In a written case you choose what to ignore. BCG's own case-prep framing still applies — structure, analysis, communication, judgment under ambiguity — but the bottleneck shifts to triage and packaging under a hard stop.
Do Big Four assessment centres always include a written case?
No. Deloitte UK lists assessment centres as one possible format and notes case studies may be on the spot or presented back, with tasks beforehand or during the interview. Other Big Four routes mix psychometrics, group work, and presentations. Treat the invitation as the source of truth.
Can I use a calculator or spreadsheet in a written case?
Follow the invitation. Bain's published case tips assume pen-and-paper for live interviews; take-home written assignments often allow normal office tools. Assessment centres sometimes ban personal devices. Ask once, early, through the official contact.
Sources
- Case Interview Preparation | BCG Careers — BCG's public description of case skills: structure, analysis, communication, and no single right answer. Checked 2026-09-24.
- Interviewing | Bain & Company — Bain's role-customized interview types, including case interviews for consulting and written assignments for some roles. Checked 2026-09-24.
- Preparing for the Case Interview | Bain & Company — Bain's published tips: clarify the objective, structure thinking, emphasize key points. Checked 2026-09-24.
- Graduates and interns | PwC's Strategy& UK — Strategy& UK structured case with slide pack and ~10 minutes of review before recommendations. Checked 2026-09-24.
- Professional Careers Assessment Support | Deloitte UK — Deloitte's public list of assessment-centre and case-study formats for professional hires. Checked 2026-09-24.