Sole trader tax return in Finland (Form 5): the parts people get wrong
A sole trader (toiminimi) files the business tax return, Form 5, in MyTax (OmaVero) by 1 April for the previous year, so the return for 2025 was due on 1 April 2026. It must be filed every year, including a year with no business activity, and it is filed in addition to checking your personal pre-completed tax return. The return is built from your books, so the bookkeeping for the year has to be finished first.
The deadline, and what lateness costs
| What | Rule |
|---|---|
| Form | Business tax return 5 (elinkeinotoiminnan veroilmoitus) |
| Deadline | 1 April, for the previous year |
| A year with no activity | the return is still required |
| Filed late, before the assessment is finished | a late-filing fee of 50 euros for the year |
| Income missing from the return | a tax increase on top of the tax |
The late-filing fee is fixed: 50 euros whether the return is two days or two weeks late. Leaving income out is more expensive, because the tax increase is calculated from the income that was added.
The parts people get wrong
The capital income share. Your business profit is split between capital income and earned income. By default the capital income share is 20 % of the net assets of the business at the end of the previous year, and capital income is usually taxed more lightly than earned income. You can ask for 10 %, or for everything to be taxed as earned income, on the return. If you never recorded what the business owns and owes, the net assets are wrong and so is the split.
The car. If you use your own car for the business, the deduction depends on a driver's log. Without a log, the Tax Administration has nothing to base the business share on. See our article on mileage allowance and per diems.
Private withdrawals. Money you take out of the business for yourself is a private withdrawal, not a cost. It does not reduce your profit, and the tax is calculated on the profit, not on what you took out.
Your own consumption. Goods from the business that you use yourself, such as stock from your own shop or food from your own restaurant, are recorded as business income at what you paid for them.
Costs that are not in the books. Some deductions are not in the accounts at all. The home office deduction, for example, goes into the field for other deductible expenses not recorded in the accounts. See our article on the home office deduction.
Receipts. Every cost needs a receipt that shows what was bought. A bank line alone is not enough. See what a receipt must show.
After filing
You can correct a filed return in MyTax by choosing to correct it, until your assessment is complete. The tax for the year is set against the prepayments you paid during it: see our article on tax prepayment. If your profit was higher than your prepayment was based on, request an additional prepayment in MyTax from December and pay it in January, and no interest is charged.
Every year, the Form 5 return for our sole trader clients is part of the monthly fee, built from books that were already right. If you want an accounting company in Finland to take it over, the prices are on the price list.
Sources
- Tax Administration: business tax return for self-employed individuals
- Tax Administration: late-filing fee and tax increase in income taxation (detailed guidance, 20.5.2026, in Finnish)
- Tax Administration: workspace costs of a self-employed person
Please note: this is general information about Finnish rules, not advice for your own situation, and the rules change. Ask us before you act on it.
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Karma Accounts is an accounting company in Finland for sole traders and small companies. We keep the bookkeeping current and file on time, and you get the amount before the due date.
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