Does “end date of tax assessment” mean the date when I should send back my Pre-completed tax return with corrections?

No, it does not. Due date for tax returns is not the same as the end date of your tax assessment process.

The due date for the tax return means the day when taxpayers can still add information and make corrections to the Pre-completed return that they have received. These dates are 1 April, 15 April, 22 April and 29 April in 2025. The due dates may vary. Please check yours on the Pre-completed tax return’s first page – or log in to MyTax to check it.

The end date of assessment is the day when the Finnish Tax Administration’s taxation process is ended. By that date, the corrections, additions, and other changes to your tax return will all be handled. You can see the end date for your assessment on the “tax decision”, which is in MyTax.

The tax assessment end date has an impact on a number of things, including:

• It determines the date when any tax refunds are paid to you, or it may determine the due date of your back taxes.
• If you check your assessment information but do not notice an error until after the end date, you will be required to make a formal claim for adjustment.
• Certain requests and claims must be submitted before the end date of assessment. If these requests and claims are not submitted in time, no appeals can be filed against the resulting tax assessment based on them. These include requests for income spreading agreements, requests for dividing the credit for household expenses between spouses, and requests for periodized taxation of pension income.