Poland VAT reporting update: What mandatory KSeF e-invoicing means for your VAT returns

From 1 February 2026, Poland will introduce mandatory e-invoicing through the National e-Invoicing System (KSeF). While much of the attention has focused on invoicing processes, this change also has direct and critical implications for VAT reporting.

As part of the KSeF mandate, the JPK_VDEK (SAF-T VAT return) schema is being updated to require new invoice reference information. These changes are not optional. If the required data is missing, VAT returns submitted to the Polish tax authority will be rejected.

Let’s take a closer look at the changes and what actions you need to take to remain compliant.

• Mandatory e-invoicing via KSeF introduces new required invoice reference fields in the JPK_VDEK (SAF-T VAT return). VAT returns missing these fields will be rejected.
  
• Each invoice reported must include either a KSeF identification number or one of the approved reference codes (OFF, BFK, or DI).
• While Avalara is updating products and templates, customers must update extractors, mappings, or custom logic to ensure the new fields are populated correctly before filing.

From 1 February 2026, most businesses operating in Poland will be required to issue invoices electronically via KSeF, the government-run platform administered by the Polish tax authority. Each invoice submitted through KSeF is either:

• Assigned a unique KSeF identification number, or
• Issued outside KSeF under specific scenarios where a KSeF number is not available.

This distinction now needs to be reflected not only in invoicing systems, but also in VAT reporting.

To support the KSeF mandate, Poland is updating the JPK_VDEK schema to introduce new mandatory invoice reference fields. Going forward, VAT reporting data must include one of the following for each reported invoice:

• A KSeF identification number, or
• One of three reference codes, where a KSeF number is not available:
  • OFF
  • BFK
  • DI

These fields are mandatory under the updated schema. If they are not present in the VAT return data, the JPK_VDEK submission will fail validation and the return will be rejected by the Polish tax authority. As there is no known grace period, data completeness is essential.

VAT returns will be rejected without the new fields

If the new KSeF-related reference fields are missing, your VAT return will not be accepted. This can create immediate compliance risk, including:

• Missed statutory filing deadlines
• Increased exposure to penalties and interest
• Manual rework under time pressure
• Audit and compliance scrutiny

Unlike some historical SAF-T changes, this update does not only affect structure — it requires new data that may not currently exist in your reporting flows.

This is not just a product update

While Avalara is updating its products to support the new schema, customer action is still required. In particular:

• These fields must be provided in the data sent to Avalara
• Avalara cannot infer or generate them if they are not supplied
• Customers using APIs, custom extractors, or SAP will almost certainly need to update their mappings or extraction logic

This makes early preparation critical.

Avalara is actively preparing to support the Polish KSeF-driven reporting changes by updating VAT reporting products to support the revised JPK_VDEK schema. Data import templates are also being enhanced to include the new mandatory fields. The planned release date is 26 January 2026, ahead of the 1 February mandate

Standard extractors are being reviewed and updated where applicable to support the new fields. These updates will ensure that Avalara systems can accept, validate, and report the required data — provided that customers supply it correctly.

To reduce the risk of disruption to VAT reporting, customers should take proactive steps. The required actions depend on how data is provided to Avalara.

Install updated extractors and templates

Once the updated Avalara extractors and import templates are released:

• Ensure they are installed and deployed promptly
• Confirm that the new KSeF-related fields are included in your data flows
• Validate that data is populating correctly before live filing

This applies to customers using standard Avalara extraction tools.

API and custom integration customers: Update your mappings

If you send VAT reporting data to Avalara via APIs, custom-built extractors, or middleware or bespoke integrations, you must update your mappings to include:

• The KSeF identification number, or
• One of the valid reference codes (OFF / BFK / DI) when a KSeF number is not available

Key considerations:

• Determine where this data originates in your invoicing or ERP systems
• Ensure consistent population across all relevant invoice types
• Validate data early using test submissions where available

Without these updates, VAT returns will fail — even if your invoicing processes are KSeF-compliant.

For SAP users, it is especially important to be aware that these are not standard SAP fields, and they are not available out of the box in standard SAP VAT reporting structures. In most cases, customers will need to:

• Implement custom extraction logic
• Use mechanisms such as BAdIs or equivalent enhancement frameworks
• Map the extracted values into Avalara’s updated templates or API fields

Given the development and testing effort typically required in SAP environments, early planning is strongly recommended.

To prepare for the February 2026 mandate, Avalara recommends the following actions now:

• Assess your current data flows
  • Identify whether KSeF identifiers or reference codes are currently captured
• Identify your integration type
  • Standard extractor, API, custom integration, or SAP
• Engage your IT and finance teams early
  • Especially important for SAP and custom solutions
• Plan testing well ahead of go-live
  • Do not wait until the first live filing in March 2026

The introduction of mandatory KSeF e-invoicing in Poland has direct consequences for VAT reporting. The updated JPK_VDEK schema requires new, mandatory invoice reference data, and returns will be rejected if this data is missing.

Avalara is delivering product and template updates ahead of the mandate, but customer action is essential — particularly for API, custom integration, and SAP customers.

By understanding the changes now and taking early action, you can avoid last-minute disruption and ensure continued compliance with Polish VAT reporting requirements.

Speak with Avalara today about overcoming your VAT challenges.