Tax interest is due if the wrong VAT amount has been reported (see here). Interest is however not levied, if you voluntarily correct the return within 3 months after the tax year. In other cases, rate of the tax interest is 4% (see here). This was temporarily reduced to 0,01% due to mitigate the effects of the coronavirus, but this ended per October 2020 (see here).
If you do not pay an assessment in time, collection interest is levied. This also applies if a delay of payment was granted. The period over which collection interest is due starts on the day after the payment due date and runs until the day on which the money is credited to the tax authorities’ account. To mitigate the effects of the coronavirus, the collection interest is lowered from March 23, 2020 to June 30, 2022 from 4% to 0.01%. From July 1, 2022, the collection interest is increased slowly: 1% from July 1, 2022, 2% from January 1, 2023, and then in 2 steps to 4% on January 1, 2024 (see here).
