Loan interest in your Swiss tax return

Deductible interest is not the same as the full loan instalment

Under the rules applying for 2026, private loan interest may be deducted from taxable income within the statutory limits. Repayment of the borrowed principal, by contrast, is not deductible as debt interest. A monthly instalment often contains both components. You therefore cannot simply enter all annual instalments as interest costs in your tax return.

The tax year, applicable rules and individual tax assessment are decisive. This article concerns private loans. A tax deduction makes financing neither free nor automatically worthwhile. You must be able to pay the instalment from your ongoing budget regardless of any later tax effect.

Which limit currently applies?

Art. 33 para. 1 letter a of the Federal Act on Direct Federal Tax limits the deduction of private debt interest to taxable income from assets plus 50'000 francs. This limit covers all relevant private debt interest, rather than a separate allowance for each individual loan. Specific statutory exclusions and the circumstances of the case still need to be considered.

The cantonal guidance explains where debts and interest should be entered in the relevant tax return and which documents are required. Use the guidance for the appropriate tax year. An older guide may explain the basic structure, but it does not replace checking the current rules. Professional assistance may be useful where there are several tax domiciles or particular personal circumstances.

Provide evidence of interest and outstanding debt

Ask your lender for the annual statement or a suitable account statement. It should show the interest relevant to the tax year and the reported debt balance. Compare the information with your contract and clarify discrepancies before filing. Keep the supporting documents with the tax return.

The period to which an amount is allocated follows the tax rules, rather than an arbitrarily selected bank transfer. The Bern guidance, for example, refers to debt interest that fell due during the tax year. Check the cantonal instructions for your case. An annual statement is more useful than estimating a fixed interest share of the instalment yourself.

If you refinance during the year, you may need statements from several lenders. Add the interest actually relevant without counting the same period twice. The new loan amount used to repay the old debt is not itself an interest expense. Fees and insurance premiums must not be treated as debt interest without checking either.

How much tax could you save?

A deduction reduces taxable income, rather than reducing the tax bill by the same amount. A deliberately simplified example: if 1'000 francs of interest is fully accepted and the assumed marginal tax rate is 20 percent, the calculated tax saving is 200 francs. Economically, 800 francs of interest expense remains. The actual effect depends on your tax assessment.

The marginal tax rate is not a fixed figure for every household. Income, place of residence and personal circumstances affect the calculation. The benefit may be small if taxable income is low or absent. Do not base a credit decision on an unchecked, flat-rate assumption of tax savings.

Distinguish principal repayment, leasing and insurance

Principal repayment reduces an existing debt and is not deductible as private debt interest. Leasing payments cannot simply be treated for tax purposes like interest on a personal loan either. The Bern guidance expressly states that leasing interest is not deductible. A component labelled “interest” in a leasing offer is therefore not automatically sufficient.

Optional payment protection insurance is not debt interest simply because it is charged together with an instalment. Have the different types of costs shown separately. A comparison of car loans and leasing should consider tax treatment as just one factor among several.

The rules change from 2029

The Federal Council has set 1 January 2029 as the date on which the tax reform changing the deductibility of private debt interest takes effect. Under the published general rule, the general debt interest deduction will then be linked to the ratio of certain rented or leased property values to total assets. This means the existing possibility of deducting personal loan interest cannot be assumed to continue unchanged.

This change matters for a personal loan running over several years, even if the loan itself has nothing to do with property. Do not automatically assume the same tax relief for later years as for 2026. Check the rules and any exceptions applying at that time against current tax information. Detailed property advice is not needed to calculate loan costs; the key point is not to promise permanent tax savings.

Compare loan costs before tax first

Initially compare offers on the basis of their actual payments. Potential tax relief can be considered as an additional factor, but it should not justify high interest or an unsuitable term. Paying less interest saves actual expenditure, even if the deduction is then smaller.

The loan cost examples help distinguish interest expense from total repayment. Before making an early repayment, you should also check the specific settlement statement and your available reserve instead of keeping a debt solely for the tax deduction.

Frequently asked questions

Can I deduct the entire loan instalment?

No. The interest portion and principal repayment must be separated. Principal repayment is not deductible as private debt interest.

Do I recover all interest paid through tax?

No. An accepted deduction reduces taxable income. The tax effect depends on your personal assessment.

Will today’s rules remain unchanged throughout the term?

No. In particular, the change to debt interest rules scheduled for 2029 must be considered when forming longer-term expectations.

Sources and date

As at 13 October 2026. The applicable rules, individual assessment and contractual documents are decisive.

• Federal Act on Direct Federal Tax, Art. 33
• Canton of Bern: 2025 guidance, debt interest
• Federal Tax Administration: tax reform taking effect in 2029

Lending is prohibited if it leads to over-indebtedness. A budget calculation is a non-binding indication and is not a credit offer.