Poland says invoice signatures not required; KSeF e‑invoices may miss cost details

Polish regulations state that an invoice does not need a signature to be valid. The document must simply contain the mandatory data such as date, number, seller and buyer details, description of goods or services, quantity, price, tax rate and total amount. The absence of a handwritten signature does not affect the tax validity of the invoice.

The introduction of the electronic invoicing system KSeF has removed the ability for recipients to add their own notes to an e‑invoice. Experts warn that many invoices contain only brief or generic descriptions, which can make it difficult to prove the purpose of a purchase during tax audits. They recommend keeping supplementary internal documents or printed copies of the e‑invoices with detailed annotations to justify cost deductions. While KSeF aims to digitise invoice handling, businesses may still need additional paperwork to meet tax authority requirements.