Can I use the same CSID for any invoice submission?
Yes. As long as the VAT Registration number on the CSID matches the VAT Registration Number on the documents. In other words, for every VAT Registration Number being tested across any API call, a CSID with the same VAT Registration Number is required. Note that the VAT Registration number can be any dummy number that meets the syntax specifications (15 digits, starting with 3 and ending with 3). Only a test Production CSID can be used for submitting invoices, credit or debit notes as well as QR codes.