Underpaid tax – you owe money

If you have underpaid tax, it means that you did not pay enough tax last year and that you have to pay this money now.

Payment deadlines

If you receive your tax assessment notice between 1 April and 30 June, the payment deadline for the first invoice is 20 August.

If your underpaid tax is NOK 1,000 or more, the amount will be split evenly between two invoices. The deadlines for payment of the two invoices depend on when you received your tax assessment notice:

  • June or earlier
    The payment deadline is 20 August for the first invoice and 24 September for the second invoice.
  • August or later
    The payment deadline for the first invoice will be 3 weeks from the date on which you received your tax assessment notice, and the second invoice falls due 8 weeks after you received your tax assessment notice.

If the payment deadline falls on a Saturday or Sunday, you may pay it within the Monday after the due date.

You must pay even if you make changes or appeal

If you do not pay the underpaid tax within the deadline, you must pay interest on the overdue payment. The interest on the overdue payment will accrue until you pay the underpaid tax.

If you do not pay the underpaid tax within the deadline of the first invoice, the underpaid tax falls due immediately with the full amount. This means that the amount you should have paid on your second invoice in September, also falls due on 21 August. Then you could have to pay interest on overdue payment on the full amount.

New tax assessment with underpaid tax
If you've received a new tax assessment notice with underpaid tax because you or we made changes to your taxes, you must pay all the underpaid tax within three weeks from the date on the tax assessment notice, at the latest. The amount you owe will not be split into several invoices, even if the underpaid tax is more than NOK 1,000.

Underpaid tax of less than NOK 1,000 must be paid in one instalment, and you'll receive one invoice. The deadline for payment depends on when you received your tax assessment notice:

  • June or earlier
    The deadline for payment is 20 August.
  • August or later
    The deadline for payment of underpaid tax is 3 weeks after you received your tax assessment notice.

You do not have to pay if the underpaid tax is less than NOK 100.

If the payment deadline falls on a Saturday or Sunday, you may pay it within the Monday after the due date.

You must pay even if you make changes or appeal

If you do not pay the underpaid tax within the deadline, you must pay interest on overdue payment. The interest on overdue payment will accrue until you pay the underpaid tax.

New tax assessment with underpaid tax
If you've received a new tax assessment notice with underpaid tax because you or we made changes to your taxes, you must pay all the underpaid tax within three weeks from the date on the tax assessment notice, at the latest.

How to pay

Well before the due date, you’ll receive an invoice with payment information.

If you do not pay the underpaid tax within the deadline, you must pay interest on the overdue payment. The interest on the overdue payment will accrue until you pay the underpaid tax. If we must take measures to collect the money you owe, you may have to pay fees and you may get a mark on your credit record.

Measures we may take when you do not pay are:

If you have not paid your underpaid tax within three years, your pensionable income may be reduced. This means that your pension could be reduced.

Pay early to avoid interest

If you realise that you have underpaid tax, you may pay the full amount right away, instead of waiting for an invoice. If you pay by 31 May, you will not have to pay any interest on the amount you owe.

1. Find the amount to pay

If you have not changed your tax return, you'll find the amount you owe in the green box at the top of your tax return. You can also find the amount on your paper tax return or in the printable version of the tax return that you can find under "My tax documents" when you are logged in at skatteetaten.no.

If you've changed your tax return and your tax amount has changed, the amount you owe will be automatically updated. You'll find the new amount to pay in the green box at the top of your tax return. If you cannot see a green box in your tax return, you can calculate the tax yourself. Please note that if it states that you are due a refund after the change, you do not have to pay extra tax.

2. Generate a KID number and find the account number

You must generate a KID number before you pay the amount to the Tax Administration.

You can pay any time, even before you receive your tax return and tax assessment notice. If you’ve paid too much underpaid tax, the overpaid amount will be refunded, including interest.

When you have paid too little tax through the income year, you have to pay interest on the underpaid tax. If you pay by 31 May, you will not have to pay any interest.

If you pay after 31 May, the interest rate is 3.51 percent. The interest is calculated from 1 July in the income year, that is the year before you submit your tax return, until you pay. This means that if you, for example, have underpaid tax for the 2023 income year, to be paid in August 2024, we calculate interest from 1 July 2023 until the payment date.

Example
You have underpaid tax of NOK 1,000 and pay the whole amount on 20 August. Then you must pay interest of NOK 40.

You have underpaid tax of NOK 10,000 and receive two invoices. You pay NOK 5,000 on 20 August and NOK 5,000 on 24 September. Then you must pay interest of NOK 417.

Why do I owe tax?

If you have underpaid tax, it's probably because the final amounts in your tax return do not correspond with the amounts calculated in your tax deduction card. You can compare the information in your tax deduction card with this year's tax return and see if they match.

Tips to avoid underpaying tax next year

Check your tax deduction card and update the information if something is incorrect. You can make changes to your tax deduction card at any time during the year.

This could be the reason why you have underpaid tax

If the interest on your loans in the year was lower than the amount that was calculated in your tax deduction card, you can end up with underpaid tax. This is because you can claim a deduction for the interest you pay. If the calculated deduction is higher in your tax deduction card than the final amount in your tax return, the result will be underpaid tax.

The same applies if you've paid off your loan or refinanced it, and therefore now pay less interest on the loan.

If you’ve had several employers or payers, these may have used your tax deduction card incorrectly. This especially applies if you had a table-based tax deduction card. Only your main source of income must deduct tax according to a table. Other employers and payers must deduct tax according to the percentage rate. If others have deducted tax according to the table, the total deducted tax is too low. Then you might have underpaid tax.
On your payslips, you can check if your employer or payer have used the part of your tax deduction card with table-based deductions or percentage rate deductions.

When you have a tax deduction card with percentage deductions, we calculate which percentage rate you must have based on all the information stated in your tax deduction card. If the salary income stated in your tax deduction card is lower than your actual income, it's probable that your percentage rate should have been higher. When the percentage rate in your tax deduction card is too low, you pay too little tax.

In the tax deduction card, we divide loans and interest on loans in the same way that the joint borrowers entered the deductions in their tax returns the previous year. If you have joint loan and the division of your loan and interest on the loan in this year's tax return is different from the division in the tax deduction card, one of you may end up with underpaid tax.

It's a good idea to check your tax deduction card once you receive it in December. If you change your tax deduction card after your employer or payer has reported the first payment to the Tax Administration in January, you'll receive a tax deduction card with percentage deductions. You must then make sure that the income is correct during the year.

Changes in your life situation may affect your tax. This could, for example, be that:

  • you are no longer a single provider
  • your child quits day care or the after-school supervision scheme
  • your journey to work is shorter
  • you work more from home
  • you have fewer workdays
  • you receive benefits from NAV

If you do not update your tax deduction card, you can end up with underpaid tax. This is because the deductions linked to these circumstances affect how much tax you have to pay during the year. If the information in your tax deduction card were incorrect, you may have paid too little tax and ended up with underpaid tax.

You must check the information in your tax return and compare it with the annual statements you have received from your employers, banks, child day care centres, after-school supervision schemes and others. If you find that any of the information is incorrect, you must correct it, because the information in the tax return affects how much tax you have to pay.

If you make changes in your tax return, the provisionally calculated tax will update automatically.

Avoid underpaying tax next year

Check that the information in your tax deduction card is correct. If something is incorrect or missing, you must update the information.