kvarskatt

Tax you still owe after your tax return has been processed, because too little preliminary tax was paid during the year. It is also called back tax, and on Skatteverket's pages underskott av slutlig skatt.

Your final tax statement (besked om slutlig skatt) shows the amount and the due date, roughly 90 days after Skatteverket's decision. You pay it into your tax account, in one go or in instalments, as long as the whole amount is there on the due date; Swish works if you have e-identification.

If you expect residual tax, you can make an extra payment early to reduce the interest charged.