# Validation

Process of checking an e-invoice against syntax rules and business rules.

## Definition

Process of checking an e-invoice against syntax rules and business rules.

## Explanation

Syntax validation checks XML structure against a schema.

Business rule validation checks requirements like totals, identifiers, and code lists.

## Related resources

- [XRechnung validator](/xrechnung-validator)

## Related terms

- [XML Schema (XSD)](/resources/glossary/schema): A formal definition of allowed XML structure and data types.
- [KoSIT](/resources/glossary/kosit): German coordination body; commonly refers to the BR-DE validation rules/validator for XRechnung.