It would be nice to extend the Invoice Id to at least 30 length. It's not country specific, but world wide need. Unfortunately, Shorter number (what means wrong number of the invoice) will be reflected in bookings and in SAF-T file (XML files required by the Authority in Poland). Manual workaround exists, to manually correct the SAF-T file before sending to government, but this is not a good approach because still the wrong number is in the system and is not the same like on reports send to tax authority which can effect on penalties as well. From July 2019 there is an addition to the regulations of the information reported in SAF-T files, stating that if information is incorrect there is a charge of 500 PLN for each mistake.