How do I pay additional advance tax?

How can I find out whether I have underpaid tax or whether I am entitled to a refund on my tax?

Calculate your tax using our tax calculator.

When will I have to pay underpaid tax?
Your underpaid tax will be triggered when your calculated tax exceeds the withholding tax and advance tax. You will have to pay underpaid tax within three weeks after the tax assessment is sent out.

Underpaid tax of more than NOK 1,000 will be split into two instalments. The deadline for the second instalment is five weeks after the first due date. Underpaid tax of less than NOK 1,000 will be waived. 

To avoid paying interest on underpaid tax, you can pay additional advance tax as a self-employed person by 31 May 

How do I pay additional advance tax?
Use the KID number and account number which you received with your tax return. As a self-employed person, you have until 31 May to pay additional advance tax.

Should I pay additional advance tax?
If you realise that you will have underpaid tax, you may wish to consider paying additional advance tax. You will then not have to pay any interest surcharge on the underpaid tax.

Pensioners and recipients of National Insurance benefits who are granted tax limitation because of low income will not have to pay interest on underpaid tax.