Almost every startup makes the same five accounting mistakes, and almost none is serious at the start. The problem comes with the first round: an investor asks for the accounts, the cap table or the months of runway, and there is no clear answer. Here are the five, why they happen and how to avoid them with a few hours a month.
Mixing personal and company finances
What happens. You pay the SAS’s software with your own card, or a personal meal with the company card. At year end nobody knows what was what.
Why it happens. At the start you are the company. It is the fastest way and seems harmless.
How to avoid it. An account and a card for the company only, from day one. If you pay for something of the company’s with your own money, keep the invoice in the company’s name and claim it back. Without a proper invoice the company cannot deduct the VAT.
Leaving the bookkeeping until year end
What happens. In December there are twelve months of unreconciled statements, missing invoices and unexplained expenses. And VAT is filed every month (or every quarter from 2027 if your turnover is up to €1M): without current books, you do it blind.
Why it happens. The product always seems more urgent. And the bookkeeping does not warn you when it falls behind.
How to avoid it. One hour a month, always on the same day: upload invoices, check the bank and clear up questions. Since 1 September 2026 your supplier invoices also reach you through an approved platform, which makes keeping order easier.
Keeping the cap table in a spreadsheet nobody updates
What happens. The cap table, who holds how many shares, is in a spreadsheet from two capital increases ago. The BSPCE promised to the team are in an email.
Why it happens. Every transaction is done in a rush and the record is left for later.
How to avoid it. Update it with every transaction: capital increase, BSA AIR, BSPCE or free shares. And check that it matches the articles, the minutes and the company’s share transfer register.
Not setting aside taxes and contributions
What happens. VAT, a corporate tax instalment or the DSN contributions fall due and no money has been set aside.
Why it happens. The VAT you charge your customers is not yours. And contributions are paid with the DSN every month, on the 5th or the 15th.
How to avoid it. Each month, set aside the VAT collected and the contributions, plus a share for corporate income tax and the CFE. We tell you the exact amount for your case.
Not watching cash
What happens. You know how much is in the bank, but not how many months you have left. The round slips by three months and the account does not last.
Why it happens. The balance is easy to check. Working out the months of runway (available funds divided by monthly net spend) needs current numbers. Late bookkeeping, again.
How to avoid it. Check three figures every month: available funds, net spend for the month and months left. Start preparing the next round when you have 9 to 12 months left, not 3.
Your five-point list
- Separate account and card for the company.
- One hour of bookkeeping a month, always on the same day.
- Cap table updated with every transaction.
- VAT, contributions and taxes set aside every month.
- Months of runway calculated every month.
If you want to go through the five points with your own case, we do it with you in our startup advisory: cap table, valuation and preparing your next round.
Figures checked against official sources on 1 November 2026. They change every year, so confirm them before you act.