Monthly Accounting Documents Checklist: Complete Guide 2026

By Hugo Ribeiro, Certified Accountant · Member of the Order of Certified Accountants · HVR Business Consulting

Introduction: Why Organizing Accounting Documents Matters

Document organization is the foundation of efficient accounting. Sending correct documents on time to your accountant ensures compliance with legal deadlines, avoids penalties, and enables informed management decisions.

1. Mandatory Monthly Documents

Purchase and Sales Invoices

  • Sales invoices issued - all invoices, receipts and debit/credit notes
  • Purchase invoices received - suppliers, services, consumables
  • Professional service invoices - lawyers, consultants, technicians

Bank Documents

  • Complete bank statements - all company accounts
  • Transfer confirmations - supplier payments and client receipts
  • Credit card statements - business card expenses

Personnel Documents

  • Payslips - salary processing
  • Employment contracts - new hires
  • Social Security communications - admissions and terminations

2. Recommended Submission Deadlines

Timely submission allows your accountant to process VAT (20th for monthly regime) and other tax obligations without delays.

3. How to Organize Documents

  • Create monthly folders on computer or cloud
  • Use consistent naming: YYYY-MM_DocumentType_Supplier
  • Digitize paper documents with good resolution

Legal Sources and References

  • CIRC - Corporate Income Tax Code
  • CIVA - VAT Code
  • Portuguese Labour Code

Last updated: January 2026

Key Takeaways

  • Send documents by 5th-10th of the following month to meet tax deadlines
  • Mandatory documents: invoices, bank statements, payslips
  • Organize digitally with monthly folders and consistent naming
  • Keep all documents for 10 years as required by law
  • Avoid penalties: incomplete documents can cost up to €3,750

FAQ

What documents should I send monthly to my accountant?

You should send sales and purchase invoices, bank statements from all accounts, personnel documents (payslips, contracts), payment confirmations and expense reports with supporting documentation.

What is the ideal deadline for sending documents?

The ideal deadline is by the 5th of the following month, with maximum deadline on the 10th. This allows the accountant to process VAT and other tax obligations on time.

How long should I keep documents?

You must keep all documents for 10 years, as established in the VAT Code and Corporate Tax Code.

What are the consequences of not sending documents on time?

Delays can make it impossible to meet tax deadlines, result in fines from €150 to €3,750, and prevent VAT deduction on undocumented purchases.

How should I organize documents digitally?

Create monthly folders, use consistent naming (YYYY-MM_DocumentType_Supplier), digitize with good resolution and use secure sharing portals.