Can I correct my tax return after the deadline in Norway?
Did you notice a mistake in your Norwegian annual tax return only after 30 April? Is a deduction missing, income from Poland not included, bank interest left out, or employer data incorrect? This happens often, especially when some documents arrive late or the pre-filled information does not match your records.
In this article, we explain whether it is possible to correctly amend your skattemelding (tax return) after the deadline, which years can still be corrected in the normal way, when you need to file an appeal, and what financial consequences a changed return may have.
Correcting a skattemelding after 30 April - rules
In Norway, you can correct your skattemelding after the 30 April deadline. This applies both when the return has been actively submitted and when it has been treated as filed with pre-filled data.
The most important rules are simple:
- after making changes, you must submit the skattemelding again - just entering corrections in the system is not enough,
- you are responsible for making sure the information is correct and complete,
- you do not need to attach documents in advance, but you must keep them in case the tax office asks for them or audits you,
- a correction may increase your refund, reduce your refund, or result in additional tax to pay.
The basis for a standard self-correction is skatteforvaltningsloven § 9-4. The rule allows the taxpayer to change previously submitted information, but the correction must reach the tax office no later than 3 years after the filing deadline. This route does not cover, among other things, cases where the tax base has already been determined by the tax office in a decision or cases under audit.
Which years can you correct in 2026
As of 28 July 2026, a standard self-correction can generally be made for the last 3 income years: 2025, 2024, and 2023. Older years require a different route, most often a klage (appeal or request to change the assessment).
| Income year | Standard route in 2026 | What this means in practice |
|---|---|---|
| 2025 | Standard skattemelding correction | You log in, correct the data, and submit the return again |
| 2024 | Standard skattemelding correction | You can fix errors or missing information from the previous year |
| 2023 | Standard skattemelding correction | This is still within the self-correction period |
| 2022 | Usually klage | A standard correction after 3 years is generally not enough |
| 2021 | Usually klage | The change must be justified through the appeal process |
If you have already received your skatteoppgjør (tax assessment showing a refund, additional tax, or a zero result), you can still correct data for years within the correction period. After the changes are processed, you will receive a new assessment.
For sole proprietorships, the annual filing deadline is different from that for regular employees and is generally 31 May. If you run an enkeltpersonforetak, the case may also require correcting business data, so it is worth checking it separately with an accounting firm (e.g. Efirma Regnskap AS).
How to correct a return after the deadline step by step
Most often, you make the correction electronically through your tax profile. You select the relevant year, update the information, and submit the skattemelding again.
Typical reasons for corrections include:
- missing deductions, e.g. interest on a loan, commuting expenses, pendlerfradrag (deduction for a person commuting between work and home), or union dues,
- incorrect income from work, NAV, pensions, or benefits,
- missing income, bank accounts, real estate, or other assets from Poland,
- incorrect data from the bank, employer, or NAV
If you are correcting deductions, also check which items may matter in your situation. We discuss more examples in the article What tax deductions are available in Norway for 2025?
If the error comes from information submitted by your employer, bank, NAV, or another institution, correcting only your own return may not solve the source of the problem. In that case, you need to contact the entity that provided the incorrect data, because it is the one that must correct the source information.
What happens after a correction - refund, additional tax, and interest
After you submit a correction, the tax office recalculates the return. If the change affects your tax, you will receive a new skatteoppgjør. Processing a correction after the assessment can take up to 8 months, so the result does not always appear immediately.
| Situation after correction | Effect | Important deadline or amount in 2026 |
|---|---|---|
| Tax after correction is lower | You may receive an additional refund | A refund below 100 NOK is not paid out |
| Tax after correction is higher | You will receive additional tax to pay | The full amount must be paid within 3 weeks from the date of the new assessment |
| You file a correction or appeal, but you still owe tax | You still have to pay on time | Missing the payment deadline causes late-payment interest |
| The additional amount is very small | It does not always have to be paid | Additional amounts below 100 NOK including interest do not have to be paid |
For a standard additional tax payment for income year 2025, it was possible to avoid underpayment interest by paying by 31 May 2026. Since that date fell on a Sunday in 2026, the practical deadline was 1 June 2026. After that date, a rate of 3.12% applies, calculated from 1 July 2025 until the due date of the first invoice.
For a revised decision or self-correction in 2026, interest of 5% applies when the liability increases and 4% when the liability is reduced. Late-payment interest on taxes in 2026 is 12% from 1 January 2026 and 12.25% from 1 July 2026.
If you are waiting for your assessment result, our article When will I get my tax refund in Norway and how can I check the status? may be helpful.
When is extra tax charged?
You are required to provide correct and complete information. If incorrect or incomplete data could have given you a tax advantage, the basic tilleggsskatt (additional tax, i.e. a tax penalty) is 20% of the tax advantage. In more serious cases, the penalty can increase to 40% or more.
Voluntarily correcting information before an audit or before the tax office obtains information from other sources may protect you from tilleggsskatt. This is especially important in cases involving undeclared income or assets abroad. These cases often also involve voluntary correction, which is described in more detail in the article Tax amnesty in Norway - avoid penalties and interest!
FAQ - frequently asked questions
Summary
- You can correct a skattemelding after the deadline, but after each change you must submit the return again.
- In 2026, standard self-correction generally applies to the years 2025, 2024, and 2023.
- Older years, such as 2022 and 2021, usually require the klage procedure rather than a standard correction.
- A correction may result in a refund or additional tax, and if additional tax is due, you must keep an eye on the payment deadline and interest.
If you need help correcting your tax return after the deadline in Norway, call us at: +47 21 38 38 21. We help Poles in Norway get their tax matters in order.
Article author: Marcin - marcin@efirma.no
