The Most Common Mistakes Candidates Make in FDD Interviews
17th October 2026
I have sat on the interviewer side of enough FDD interviews to see the same mistakes repeated. Most are avoidable and none of them relate to how sharp the candidate is.
But I will be honest, some are genuinely unavoidable. If you are inherently unlikable, these people will not want to be in the trenches with you during sprints on report delivery…
TECHNICAL MISTAKES
Confusing the accounting with the deal - Candidates recite the definition of EBITDA correctly but cannot explain why a buyer would adjust it (e.g. a one-off legal settlement that should be stripped out, or an under-market owner salary that should be normalised). The interviewer wants to hear the “why”, not the textbook definition.
NWC in a deal - NWC is about cash timing and the price paid at completion. If you cannot explain what a peg is, or why seasonality matters when setting it, other candidates will impress.
Ignoring the cash conversion point – Understand why a business can still have a strong EBITDA profile, but worsening cash conversion. It is rare for it to be asked, but a great opportunity to stand out.
Overclaiming skills - Don’t get caught out with an oversell you can’t back up.
Experience - Be ready to explain something interesting in engagements/projects detailed in your CV (see previous blog post on CV building).
BEHAVIOURAL MISTAKES
Not knowing the firm - Candidates often cannot name a recent deal the team worked on, or explain the difference between FDD and the other service lines (e.g. valuations, M&A advisory). Unfortunately, as with many businesses, only reading the ‘services’ on a company’s website won’t tell you the real answer – speak to someone. Also, look up your interviewers most recent deal involvement, LinkedIn makes this easy to find these days. Ask a sensible question/appear interested.
Vague “why FDD” answers – You have to appear genuinely interested, otherwise you will be put into the bucket of “someone who doesn’t like audit”.
No questions at the end - Having nothing to ask suggests limited interest. Prepare two or three sensible questions (e.g. team structur, typical deal mix, how work is allocated).
Case Study Mistakes
Jumping to a conclusion - Candidates see a revenue decline and immediately call it a red flag. Ask what drove it first (e.g. a lost customer, a pricing change, a disposal) before offering a view.
Not stating assumptions - If the data is incomplete, say what you would assume and why. I would rather see a clearly stated assumption than a silent guess.
Forgetting the purpose of the work - The output is a view for the buyer on price and risk. A list of observations without a “so what” is not useful.
All you need to know
The below information pack (60+ page document with accompanying example Excel databook) will benefit any individual looking into a potential move into the financial due diligence profession (often referred to as transaction services or transaction advisory services in the market). The information pack will prove useful for potential interview questions or even simply establishing a general understanding of the typical financial due diligence thought-process.
The pack will also be beneficial for any already successful FDD candidate who is looking to acquire a strong technical understanding in order to hit the ground running.E
FDD Interview Preparation Pack and Example Excel Databook
Complete FDD (Transaction Services) interview preparation pack (60+ page document + example Excel databook). Insights into the FDD process and detailed technical examples covering all three key FDD workstreams: Quality of Earnings, Net Debt and Net Working Capital.
Candidate feedback on the interview preparation pack:
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“Thanks to the wide range of information, I successfully managed to receive a job offer at a Big4 firm in FDD.” — Guido V, March 2026
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