Written case interview: how it works and how to pass

In a written case interview you receive a pack of documents, work alone for a set time, and then present your recommendation. It tests the same thinking as a normal case, plus two things a spoken case cannot: finding what matters in too much information, and writing it down clearly. Bain and BCG use it in some offices' later rounds, and many boutiques and Big Four strategy teams use a version of it.

Typical format

A method that fits in an hour

1. Read the question first (2 minutes). Write the decision the client must make at the top of your page.
2. Skim everything (8 minutes). Mark each page: useful, maybe, ignore. Most packs contain pages that are there to distract.
3. Form an early answer (5 minutes). Decide what you think and what would have to be true.
4. Do the three or four calculations that test it (20 minutes).
5. Write the slides (20 minutes). One message per slide, written as a full sentence in the title.
6. Rehearse the first minute (5 minutes).

What good slides look like

• Slide 1: the recommendation and the three reasons.
• Slides 2 to 4: one reason each, with one chart or table and the number that proves it.
• Last slide: risks and next steps.

Hand-drawn is normal. Interviewers mark clarity, not design.

Common mistakes

• Reading every page carefully and starting to write with ten minutes left.
• Slides with a topic as the title ("Market overview") instead of a message ("The market is growing 8% a year, mostly in cities").
• Changing your answer under questioning without a reason. Change it only if the interviewer shows you a fact you missed.

To practise, take any full case, give yourself 45 minutes without help, and write three slides before you look at the model answers.