As the government website explains, the mandatory use of official e-invoices is being phased in. At present we are in the "voluntary phase" - companies may choose to issue the new e-invoices or traditional paper or soft invoices.
As of 1 July 2024 all active VAT companies will be required to issue the new e-invoices, with companies exempt at that time following suit from the beginning of 2025.
The Ministry of Finance has announced that it is currently working on detailed instructions for foreign companies operating in Poland to clarify when and in what circumstances they too will be required to avail themselves of the new invoices.
Sources: gov.pl, bankier.pl
pt