B-skat: how tax works when you're self-employed
Written by Mads Antonsen · bookkeeper at Numina
Updated July 17, 2026
There's no employer to withhold your tax when you run a sole proprietorship. Instead you pay B-skat in instalments over the year — calculated from the profit you yourself enter on the preliminary income assessment (forskudsopgørelse). Here's the system, the deadlines and the traps.
How the system fits together
The profit in your sole proprietorship is personal income: you pay 8% labour-market contribution (AM-bidrag) and then ordinary income tax on it. But the tax is collected provisionally — you enter your expected profit on the forskudsopgørelse (field 221), and the Tax Agency converts it into B-skat instalments. After year-end, everything is settled in the annual tax assessment.
The instalments: 10 per year
B-skat is paid in 10 equal instalments — every month except June and December. Each instalment falls due on the 1st of the month, with the 20th as the final day to pay on time. Every instalment covers both tax and AM-bidrag, and you pay via TastSelv or direct debit (Betalingsservice).
The forskudsopgørelse is your most important tool
If your actual profit misses what you registered, you end up with residual tax or excess tax. So adjust the forskudsopgørelse as soon as you can see the year turning out better or worse than expected — it can be changed at any time on skat.dk, and the remaining instalments are recalculated automatically.
That of course requires knowing what your profit actually is right now — one more reason to keep the bookkeeping current all year instead of once a year.
Your first year: the classic trap
The Tax Agency doesn't know your new business, so no B-skat instalments appear automatically when you start. If you do nothing, you pay zero tax on the business all of year one — and get the whole bill as residual tax with a surcharge the year after. Update the forskudsopgørelse as soon as you're up and running.
The tax return and annual assessment
As self-employed you must complete the extended tax return (oplysningsskema) with the business's result every year — the deadline is 1 July in the year after the income year. Then comes the annual assessment, and any residual tax is collected with a surcharge. The basis is your bookkeeping, so up-to-date accounts make the return a formality.
Numina keeps the numbers ready
Numina's bookkeepers and AI keep your books current, so you can always see your actual profit in the app — and adjust the forskudsopgørelse on real numbers instead of a gut feeling. We file your VAT automatically, and the figures for the tax return are ready when the deadline approaches.
Stop keeping track of all this yourself
Numina's bookkeepers and AI handle bookkeeping, VAT and deadlines for you — at a fixed price with no lock-in. Accounting software included.
What's the difference between A-skat and B-skat?
A-skat is withheld by an employer before salary is paid out. B-skat you pay yourself, in instalments, on income that hasn't been taxed at source — typically business profit and fees.
What happens if I miss an instalment?
Interest accrues until you pay. If the real problem is that the instalments are set too high, don't just skip them — adjust the forskudsopgørelse instead, and the instalments are recalculated.
Do I pay B-skat on dividends from my ApS?
No. Dividends are taxed as share income, and the company withholds the dividend tax when it's paid out. B-skat is about personal income with no tax withheld at source — such as profit in a sole proprietorship.