Late payment interest calculator

Calculate late payment interest on an overdue amount.

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1. Basis

Principal amount krDue date Interest start date End date (incl.)

Number of days30 daysStart and end dates are both included.

2. Interest rate

Reference rateReference rate %Statutory surcharge %

Late interest (reference + surcharge)10.00 %

Default: 2.00% for 2026-07-01/2026-12-31. Verify the rate for the debt period.

3. Fees (optional)

Reminder fee krCollection cost krAdministration fee kr

Import data (optional)

CSV or Excel. The first data row is imported.

Result Calculation ready

SEK (kr)

The calculation is based on 30 days.

PrincipalSEK 10,000.00

Late interest (10.00 %)SEK 82.19

Reminder feeSEK 60.00

Collection costSEK 180.00

Administration feeSEK 0.00

Total dueSEK 10,322.19

The interest rate follows the entered values.
This calculation is informational and is not legal advice.

4. Calculation details

Period	From	To	Days	Rate	Interest
1	26/09/2026	25/10/2026	30	10.00 %	SEK 82.19

Interest formulaInterest = Principal × Rate × Days / 365SEK 10,000.00 × 0.1000 × 30 / 365 = SEK 82.19

Uses the statutory base formulaReference rate + 8 percentage points as the default surcharge.

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