KSEF-006:Unit code not recognized
Fix: Use Polish unit codes from the official classification. Provide the required value in the free validator.
Unit of measure must be from Polish classification. Common codes include szt. (piece), kg, m, l, usł. (service).
Engine Classification
Business data required · Explicit input workflow · No assumptions made
Required input: Unit of Measure
What is KSEF-006?
KSEF-006 is a fatal validation rule defined in the KSeF specification (POL national rules).
When this rule fires, the invoice is rejected by Peppol access points and never reaches the buyer.
Why This Error Matters
KSEF-006 is a hard failure — the invoice must be corrected and re-sent before it can reach the recipient.
Validator Behavior
- ·Causes invoice rejection
- ·Error returned: KSEF-006
- ·Specification: KSeF
How to Fix It
Technical Reference
Code Example
<JednostkaMiary>szt.</JednostkaMiary>Common Causes
- ·Using English unit names
- ·International codes not mapped
- ·Invalid abbreviation
Seeing this in production? The API handles KSEF-006 automatically. See the fix response →
Frequently Asked Questions
Unit of measure must be from Polish classification. Common codes include szt. (piece), kg, m, l, usł. (service).
Use Polish unit codes from the official classification. Invoice Navigator detects this error and prompts for the required business data before applying a safe fix.
Yes, KSEF-006 is a critical error that will cause invoice rejection. It must be fixed before submission to ensure your invoice is accepted by the recipient's system.
KSEF-006 requires specific business data to resolve. Invoice Navigator detects the error and guides you through providing the needed information, then applies the fix with full audit documentation.
Related Content
Last updated: 3 March 2026
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