The system since 2023: you pay contributions on what you think you’ll earn

Since the reform of the self-employed contribution system, you no longer freely choose any contribution base: you pick a bracket based on your projected annual net income, and pay contributions month by month according to that projection. The problem is that this projection, almost by definition, rarely matches exactly what you end up actually earning.

Why the adjustment arrives almost 2 years late

Social security can only check your actual net income once the tax office has closed your tax return for that year — and that return is filed the following year (year 1’s return is filed in spring of year 2), and matching that data against social security records isn’t instant. The practical result: the adjustment for what you paid in year 1 can land well into year 3. When it does, one of two things happens:

  • You underpaid compared to what you actually earned → you’re billed for the difference, usually with a deadline to pay it.
  • You overpaid → you get the difference refunded.

Why it catches so many people off guard

Since almost two years have passed since you earned that money, it’s easy to no longer have that margin “set aside” — you’ve got used to a different level of spending, or simply forgotten about it. Getting hit with a bill for several hundred euros out of nowhere, for a year you’d already considered closed, is why this issue generates so many complaints every time the adjustment letters go out.

How to soften the shock (you won’t eliminate it entirely)

  • Adjust your income projection during the year itself, not just when you register: the system lets you change contribution bracket several times a year as you see how your business is actually going, instead of waiting to be told after the fact.
  • Base your projection on real figures, not just last year’s number — if your business is growing or shrinking, your contributions should move with it during the year, not only at year-end.
  • Mentally set aside a buffer for a possible upward adjustment, just as it’s recommended to set aside money for taxes: don’t treat 100% of what you invoice as already spent.

Don’t let it catch you the same way two years running

If you’d like us to review your contribution projection against your actual figures for the current year, instead of waiting for the letter from social security, let’s talk before you end up paying an adjustment that could have been corrected in time. Write to us at contacto@asesoriamadal.es.