Regulatory updates - Portugal

Under the Proposed Law No. 110/XVII/2nd, PDF invoices would continue to be accepted as electronic invoices for tax purposes until December 31, 2027. This would effectively postpone by one year the application of the authenticity and integrity requirements, including QES, that were expected to apply to PDF invoices from January 1, 2027. In addition, the deadline for submitting SAF-T accounting files relating to periods beginning in 2028 would be deferred to 2029 and subsequent years.

The State Budget proposal must be approved by the Assembly before taking effect. Debate and voting in general are scheduled for October 27–28, 2026, followed by the final vote on November 24, 2026.

The Circular Letter No. 25120/2026 replaced the outdated guidance in Circular Letter No. 33129/1993 taking into account digital invoicing practices and recent changes introduced by Decree-Law 97/2026.

Key regulatory changes 

• Credit notes may only be used to amend invoice data and cannot be used to cancel invoices. 
• Formal invoice errors (e.g., incorrect VAT number or customer details) must be corrected through cancellation and issuance of the new invoice.
• Credit and debit notes are required when the taxable amount or VAT changes.
• VAT reductions require objective evidence that the customer received the correction or was reimbursed. Electronic acknowledgements, customer portal logs and similar digital records are recognized as valid proof. 
• The Circular distinguishes procedures and deadlines applicable to transaction changes, billing errors and legal qualification errors. 
• Additional guidance is provided on VAT adjustments linked to the new housing incentive regime introduced by Decree-Law 97/2026.

Transitional measure

The Circular recognizes that some invoicing systems cannot yet issue credit or debit notes correcting only the VAT amount. Until December 31, 2026, taxpayers may instead cancel the original invoice by credit note and issue a replacement that references the original document and retains the original transaction date.

Action required

From 2027, businesses must use targeted corrective documents in line with the new guidance. Organizations should therefore update their invoicing and ERP processes by the end of 2026 to avoid more complex corrections, including possible amendments to previously filed VAT returns.