It is not mandatory to add tax prepayments to single-entry bookkeeping, but this is recommended, so that you are able to keep track of your business' finances.
As a trade name entrepreneur, you will have to apply for prepayment tax in MyTax. After you have applied, you will get a decision letter from the Tax Office. You can then add this decision letter to the service.
Which voucher is accepted for tax prepayments?
An acceptable voucher for prepayment tax is the decision letter, tax prepayment invoice (downloadable from MyTax) or a receipt of the bank transaction.
If the amount of prepayment tax changes, please add the new decision letter to the service.
If you work as a part-time entrepreneur, you might also be able to pay tax prepayments using your employment tax card. Please contact the Tax Office regarding the instructions for this.