KSEF-001:NIP validation failed

Polish NIP (tax identification number) must be 10 digits with valid checksum. Both seller and buyer NIP are required for B2B invoices. Leading zeros are significant.

Verify the NIP is 10 digits with valid checksum. You can also use Invoice Navigator's automatic Fixer tool to correct this instantly.

Yes, KSEF-001 is a critical error that will cause invoice rejection. It must be fixed before submission to ensure your invoice is accepted by the recipient's system.

Many instances of KSEF-001 can be automatically corrected using Invoice Navigator's Fixer tool. Upload your invoice and the tool will identify and fix common issues, including nip validation failed.