KSeF 2.0 Invoice Attachments: Mandatory Notification Rules from 2026

The Ministry of Finance has introduced a new rule in KSeF Poland e-invoicing that businesses must follow starting 1 January 2026.

From this date, companies cannot send invoices with attachments in KSeF 2.0 unless they notify the tax authority first. This applies to all businesses using e-invoicing in Poland, regardless of size or industry.

If your business plans to send invoices with attachments or stop sending them, you must inform the tax authority through the e-Tax Office.

What is changing in KSeF 2.0

Until now, many businesses assumed attachments could be added freely. That is no longer the case.

From 1 January 2026:

• You must submit a notification before sending invoices with attachments
• You must also notify if you want to stop using attachments
• Approval is required before attachments are allowed
• The approval process can take up to 3 working days
  
  

This rule is part of Poland?s preparation for the KSeF mandatory date of 2026.

Application Guidelines and Mandatory Information

To notify your intention to issue invoices with attachments, access the e-Tax Office module and submit the application form, which requires the following key details:

• Taxpayer Information: Include your basic details, such as name, address, and a valid email address for confirmation notifications.
• Activity Types: Specify the business sectors involved, for example, electricity supply, telecommunications services, or fuel supplies.
• Technical Parameters: Provide estimates of the average monthly invoice volume and typical file size in kilobytes.

• Purpose: To include detailed, complex tax-related data that doesn't fit easily in the main invoice body (especially useful for utilities/electricity/gas suppliers, telecom services, fuel suppliers, where there are many measurement points, varying quantities, units, or unit prices).
• Allowed content: Only tax-related information (as per Art. 106e ust. 1 VAT Act) or data strictly connected to it (e.g., detailed breakdowns of quantity, units of measure, net unit prices, consumption per point of delivery, etc.).
• Not allowed: Marketing materials, promotions, contracts, acceptance protocols, price lists, guarantees, instructions, or any non-tax/business documents.
• Note: Sending prohibited content may result in losing the right to issue invoices with attachments in KSeF 2.0.
• Size: Attachment size limits are removed from the law and will be defined in KSeF interface specifications.

• Using attachments is optional, not mandatory, but you must notify the tax office first to enable the feature technically.
  
  

Why Notification is Required

• To use the attachment function in KSeF 2.0, taxpayers must first notify their intention via e-Urza?d Skarbowy.
• This is a formal requirement without notification and approval; the system will not accept invoices with attachments from you.
• You can also notify later to stop using attachments if your needs change.
• The process is simple, fully online, and processed quickly ((max.3 business days).
  
  

Steps to Notify Intention to Issue and Send Invoices with Attachments

1. Log in to e-Urza?d Skarbowy (e-Tax Office)
Go to the official portal: https://www.podatki.gov.pl/e-urzad-skarbowy/Log in securely using:

• Profil Zaufany (trusted profile)
• e-dowód (electronic ID)
• Bank credentials
• mObywatel app (If you don't have access, create a trusted profile at login.gov.pl first.)
  
  

2. Find the Notification ModuleIn the e-Urza?d Skarbowy dashboard, locate the section/module for KSeF 2.0 notifications (available since 1 January 2026).

3. Look for: "Notification of intent to issue and send invoices with attachments to KSeF 2.0" (Zg?oszenie o zamiarze wystawiania i przesy?ania do KSeF 2.0 faktur z za?a?cznikiem).

4. Fill Out the Simple FormProvide:

• Your details (including NIP and email address)
• Type of business activity (e.g., electricity supply, telecommunications, fuel supply)
• Estimated technical parameters: average monthly number of invoices with attachments + average invoice size (in kilobytes)
  
  

5. Submit the Notification

• Individuals with NIP: Submit in your own name.
• Companies/non-natural persons with NIP: Submit via an authorized organization account user (UKO). Submit electronically through the portal.
  
  

6. Wait for Processing Applications are processed in order of receipt. Maximum time: 3 business days. You will receive email updates (to the address provided) about status and approval.

7. Start Using After Approval Once you receive the confirmation email, you can begin issuing and submitting invoices with attachments in KSeF 2.0.

Steps to Stop Issuing Invoices with Attachments (If Needed Later)

1. Log in to e-Urza?d Skarbowy (same as above).
2. Find the section for: "Notification to cease issuing and sending invoices with attachments" (Zg?oszenie o zamiarze zaprzestania wystawiania i przesy?ania do KSeF 2.0 faktur z za?a?cznikiem).
3. Submit the notification (similar form and details required).
4. Processing takes up to 3 business days.
5. After approval, you can continue with standard invoices in KSeF (without attachments).

What This Means for ERP and Automation

Businesses using ERP systems must ensure their setup supports:

• Embedded XML attachments
• Validation rules from KSeF API documentation
• Smooth KSeF integracja z systemem ERP

Manual tools or basic invoicing software may not be sufficient. Many companies are now reviewing KSeF software solution Poland, oprogramowanie do e-faktur KSeF, or full KSeF system integration guide support.

Even where KSeF exemptions 2026 apply, attachment rules must still be followed when used.

Prepare Early for KSeF 2026

The shift to mandatory e-invoicing is not only about compliance it affects billing speed, data accuracy, and system stability. Businesses still learning fakturowanie co should treat this notification rule as a clear signal to prepare early.

Choosing the right e-invoicing service provider in Poland and compliant oprogramowanie do fakturowania elektronicznego KSeF Polska can prevent last-minute disruptions.

KSeF 2026 is approaching fast. If your business issues complex invoices or plans to use attachments, now is the time to act.

Talk to Taxilla to understand your KSeF readiness, ERP integration needs, and attachment compliance under KSeF Poland e-invoicing before the deadline puts pressure on your operations.