The interest deduction is one of the most valuable, and most misunderstood, parts of Swedish personal finance. If you pay interest on a loan you get part of it back through tax, which means the real cost of borrowing is lower than the rate looks. For most people it happens almost automatically, but there are pitfalls: the deduction can shrink or vanish, and how you split it as a couple can make a difference. Here is the whole picture.
You get back 30% of your interest costs up to 100 000 kr per person per year, and 21% on the part above that. From 2026 it only applies to loans with collateral, such as your mortgage or a car loan; interest on unsecured loans and card credit no longer counts. The deduction is really a tax reduction: it counts against your tax and requires you to have tax to offset it against. The bank reports the interest automatically, so it is usually pre-filled in your tax return. If you borrowed together you can split the deduction between you.
I will cover how the deduction is worked out, what qualifies, whether it happens automatically, how you split it as a couple, and when there is no deduction at all. Run your own loan in the mortgage calculator.
How the deduction is worked out
The deduction has two levels. On the first 100 000 kr of interest costs per person per year you get back 30%. On interest above that it drops to 21%. Technically it works so that the interest creates a deficit in the capital income category, and on the deficit you get a tax reduction. That is why the real cost of a loan at, say, four percent interest is in practice closer to 2.8 percent after the deduction. That detail alone changes the whole comparison between borrowing, amortising and saving.
What qualifies for the deduction
Since 1 January 2026 only loans with collateral qualify: a mortgage on a house, tenant-owned flat (bostadsrätt) or holiday home, a car or boat loan secured on the vehicle, or a loan against listed securities or fund units. The lender also has to be in the EEA (European Economic Area) or a country that exchanges tax information with Sweden. Interest on unsecured personal loans (blancolån), card credit and most private loans gives no deduction at all any more; 2025 was the halfway year. What qualifies is the interest itself, not fees. Amortisation, on the other hand, never qualifies; it is repayment of the loan itself, not a cost. The same goes for arrangement and invoice fees. The point is to separate the interest, which is the price of borrowing and qualifies, from the amortisation, which builds your own capital but is not deductible. So a mortgage where you both amortise and pay interest qualifies only on the interest part.
Does it happen automatically?
Mostly, yes. Banks and lenders report to the Tax Agency how much interest you paid, so the figure is almost always pre-filled in your tax return and the deduction is worked out for you. Your job is to check that the amount is right, especially if you have had loans with several lenders or borrowed privately from someone, since a private lender does not report automatically and you have to enter the interest yourself. The deduction then shows up as an item in your final tax statement and affects whether you get money back or have to pay residual tax.
Splitting the deduction as a couple
If you have a joint loan you can split the interest between you, and this is where you can optimise. Because the lower level of 21% only kicks in when one person's interest exceeds 100 000 kr, it often pays to split the interest evenly so neither of you goes above that line. Just as important: the deduction requires you to have tax to offset it against. If one partner has very low or no income, the deduction can partly be lost for that person, and then it is better to put the larger share on the one with income. You make the split easily in the tax return.
A worked example
Say you paid 40,000 kr in interest during the year. Since that is below 100 000 kr you get back 30%, that is 12,000 kr, through tax. If you instead paid 130,000 kr in interest in an expensive year it becomes two levels: 30% on the first 100,000 = 30,000 kr, plus 21% on the last 30,000 = 6,300 kr, a total of 36,300 kr back. That is money that either lowers your residual tax or shows up as a tax refund. Work out what the interest and the deduction mean for your monthly cost in the mortgage calculator.
My recommendation
Do not forget the deduction when you think about your housing cost; the interest you see on paper is about 30 percent lower in reality. Check that the pre-filled interest is right in your tax return, and if you have a joint loan, split it so you both stay on the higher deduction level and the one with income can use the deduction. To understand the interest itself better, read the guide to mortgage rates, and when tax-return season approaches, the guide to filing your tax return.