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Late payment interest calculator
Work out the interest a tenant owes on unpaid rent in Belgium: at the legal rate of each year, or at the rate in the lease.
Late payment interest
Enter each unpaid amount with its due date and press Calculate. The result shows the interest on each amount and the total owed.
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Interest on unpaid rent in Belgium, in short
From when does interest run?
Under the Civil Code, interest on a sum of money runs from the day the debtor is formally put on notice to pay: a mise en demeure (ingebrekestelling), usually a registered letter. If the lease says that interest is due from the due date without any notice, it runs from each due date instead.
Which rate applies?
The rate the lease sets, or else the legal interest rate. The legal rate is fixed for each calendar year from the twelve-month Euribor of the previous December, plus two percentage points, and published in the Belgian Official Gazette. A debt that runs over the end of a year earns each year's rate for the days in that year.
| Year | Legal interest rate |
|---|---|
| 2026 | 4.50% |
| 2025 | 4.50% |
| 2024 | 5.75% |
| 2023 | 5.25% |
| 2022 | 1.50% |
| 2021 | 1.75% |
| 2020 | 1.75% |
| 2019 | 2.00% |
| 2018 | 2.00% |
| 2017 | 2.00% |
| 2016 | 2.25% |
| 2015 | 2.50% |
| 2014 | 2.75% |
| 2013 | 2.75% |
| 2012 | 4.25% |
| 2011 | 3.75% |
| 2010 | 3.25% |
How is the interest calculated?
Each unpaid amount is counted on its own, by the day, from the day interest starts until the day it is paid:
amount × rate × days ÷ 365
The interest is simple: interest already owed does not earn interest of its own.
Can the lease ask for more?
In the Brussels-Capital Region, a lease signed or renewed since 1 November 2024 may not charge more than the legal rate, nor add a fixed penalty for paying late. In Flanders and Wallonia a lease can set its own rate or a penalty clause, but a judge can reduce one that is clearly out of proportion to the landlord's loss.
How do I claim it?
Send the tenant a registered letter listing the unpaid amounts and asking for payment within a set time, with the interest from that date. If they still do not pay, the justice of the peace of the district where the property lies hears rent claims, whatever the amount.
This calculator is for information only and is not legal advice; the lease and the courts decide. Legal rates as published in the Belgian Official Gazette, last checked in October 2026.