Pursuant to the new regulations, there is the transitional period which stipulates that fiscal receipts are recognized as simplified invoices whenever issued in accordance with the VAT Act. Thus there is no need to indicate them separately in the new JPK_VAT file. The derogation in force until 31 December 2020.
The simplified invoice is a fiscal receipt up to the amount of PLN 450 gross (EUR 100), whenever it contains the buyer's tax identification number
Source: The Ministry of Finance