According to the new rules, tax liability will arise based on one of three key dates:
- the date specified in the invoice as the date of delivery;
- the date of registration of the cash register receipt;
- the date when payment was received.
It is important to note that if an entrepreneur receives an advance payment, this payment is included in the taxable base in the reporting period when the funds were actually received, even if the goods have not yet been shipped or the services have not been provided.
The STS also reminded that the object of taxation for sales tax is the sale of goods, works, or services, paid for both in cash and cashless ways. Thus, advance payments should be reflected in the reporting at the moment of their receipt.
As a result, when preparing reports for the single tax and sales tax, taxpayers must sum all receipts for the reporting period, including advance payments, in the corresponding lines where revenue volume is indicated.
The agency urged taxpayers to consider these new requirements when preparing reports for 2026.
