German Practice Management FHIR Profiles (R4) - Local Development build (v0.71.0) built by the FHIR (HL7® FHIR® Standard) Build Tools. See the Directory of published versions

Steuer-Compliance

Steuer-Compliance in der ambulanten Praxis

This page documents the tax-compliance architecture for German ambulatory practice management FHIR profiles — covering VAT (Umsatzsteuer) categorization, exemptions, and the Kleinunternehmerregelung.

Trennungsprinzip

German ambulatory practices frequently provide both VAT-exempt and VAT-liable services in the same billing cycle:

FHIR Implementation: Each Invoice carries the invoice-level tax category and exemption reason via extensions:

• ext-tax-category — UNECE-5305 / EN 16931 category code (S / AA / E / AE / Z), see TaxCategoryDE ValueSet. Context: Invoice, ChargeItemDefinition.propertyGroup.priceComponent.
• ext-tax-exemption-reason — legal basis for exemption, see UStBefreiungsgrundVS. Context: Invoice, ChargeItemDefinition.propertyGroup.priceComponent.

Both extensions apply at the Invoice root level for final billing classification, and optionally on ChargeItemDefinition.propertyGroup.priceComponent as a non-binding default suggestion in the service catalog (see ChargeItemDefinition-Pattern section below).

For per-line-item tax category in mixed invoices, use the standard FHIR field Invoice.lineItem.priceComponent.code directly (bound to the TaxCategoryDE ValueSet) — no extension is needed. This produces legally compliant ZUGFeRD / XRechnung output where each line item carries its own EN 16931 category code.

ChargeItemDefinition-Pattern

Schichtenmodell: Katalog → Profil → Spezialisierung

The tax extension pattern spans three layers of the German FHIR terminology and profile ecosystem:

fhir-terminology-de                fhir-praxis-de              fhir-dental-de
(Katalog-Lieferant)               (Pattern-Layer)             (Spezialisierung)
        |                               |                             |
        |  TaxCategoryDE ValueSet       |  ext-tax-category           |  ZahnPraxisInvoiceDE
        |  (UNECE-5305 codes:           |  ext-tax-exemption-reason   |  ZahnChargeItemDef
        |   S, AA, E, AE, Z)           |  Context:                   |  -- inherits pattern
        |                              |   Invoice,                  |
        |                              |   ChargeItemDefinition      |
        |                              |   .propertyGroup            |
        |                              |   .priceComponent           |
        +------------------------------> -----------------------------> 
             provides codes                 defines context               uses profile

fhir-terminology-de acts as the authoritative catalog supplier for the TaxCategoryDE ValueSet. The codes (S, AA, E, AE, Z) are sourced from the UNECE Recommendation N20 standard (urn:un:unece:uncefact:codelist:standard:5305). See fhir-terminology-de for the full catalog.

fhir-praxis-de defines the extension pattern (this IG) — where the extensions can be applied (Context) and how they are bound (TaxCategoryDE, UStBefreiungsgrundVS).

fhir-dental-de and other specialty IGs inherit the pattern and apply it to their specific service definitions.

ChargeItemDefinition as Catalog with Tax Pre-Population

A ChargeItemDefinition can carry a non-binding tax category suggestion on its propertyGroup.priceComponent. This serves as a pre-population hint for the PVS (practice management software) when generating an Invoice:

ChargeItemDefinition (catalog entry)
  └── propertyGroup[0]
        └── priceComponent[0]
              ├── type = #base
              ├── amount = 13.50 EUR
              └── extension[ext-tax-category]
                    └── valueCodeableConcept = UNECE-5305#E  ← pre-population hint (optional, 0..1)
              └── extension[ext-tax-exemption-reason]
                    └── valueCodeableConcept = UStBefreiungsgrundCS#para4-nr14a  ← hint (if E)

Invoice (actual billing document)
  └── extension[ext-tax-category]  ← FINAL classification (set by PVS/Steuerberater)
        └── valueCodeableConcept = UNECE-5305#E
  └── extension[ext-tax-exemption-reason]
        └── valueCodeableConcept = UStBefreiungsgrundCS#para4-nr14a

Design Decisions and Disclaimers

Default is optional (0..1): The ext-tax-category extension on ChargeItemDefinition.propertyGroup.priceComponent is entirely optional. Not every catalog entry carries a tax suggestion — in particular:

• Context-dependent codes (e.g. BEMA/GOZ codes): A BEMA code may be exempt (§4 Nr. 14a UStG) when billed by a licensed dentist, but taxable when the same service is performed by a non-licensed entity. The ChargeItemDefinition does not carry a default in these ambiguous cases.
• Mixed-use services: Services that can be both therapeutic (exempt) and cosmetic (taxable) carry no default.

Final classification is the PVS/Steuerberater responsibility: The tax category on ChargeItemDefinition.propertyGroup.priceComponent is an informational pre-population hint, not a legal declaration. The PVS must apply context-specific rules (type of practice entity, patient relationship, service purpose) and the final Invoice must reflect the actual legal classification as validated by the practice's tax advisor.

Cross-reference: The TaxCategoryDE ValueSet codes are defined in UNECE Recommendation N20 and mapped to EN 16931 / ZUGFeRD / XRechnung standards. The German FHIR terminology ecosystem provides these codes via fhir-terminology-de.

Example Instances

This IG provides three ChargeItemDefinition demo instances showing the tax extension pattern:

Kleinunternehmerregelung (§ 19 UStG)

The Kleinunternehmerregelung exempts practices below revenue thresholds from charging VAT. Since 2025 the thresholds are:

• 25,000 EUR prior-year revenue (Vorjahresumsatz)
• 100,000 EUR current-year revenue (laufendes Jahr, new hard limit since 2025 reform)

Organization Flag

The KleinunternehmerregelungExt on Organization (profile PraxisOrganizationDE) marks whether the practice is currently operating under § 19 UStG:

Organization
  └── extension[kleinunternehmerregelung]
        ├── extension[aktiv] = true
        └── extension[gueltigAb] = "2025-01-01"

Invoice Constraint

The PraxisInvoiceDE profile enforces via FHIRPath invariant ku-hinweis-required that invoices flagged with ext-ku-hinweis-pflicht = true must contain Invoice.note with the statutory notice:

„Gemäß § 19 UStG wird keine Umsatzsteuer berechnet."

FHIRPath expression:

extension.where(url='https://fhir.cognovis.de/praxis/StructureDefinition/ext-ku-hinweis-pflicht')
  .value.ofType(boolean).first() = true
implies note.text.exists()

Note: FHIRPath in FHIR R4 cannot traverse external references (Invoice → Organization). The ext-ku-hinweis-pflicht boolean extension on Invoice therefore acts as a signal set by the invoicing system when it detects the issuing organization is a Kleinunternehmer — the validator then verifies the note is present.

Tax Category for KU Invoices

KU invoices use:

• ext-tax-category = E (exempt)
• ext-tax-exemption-reason = kleinunternehmer-para19

Abfärbetheorie

The Abfärbetheorie (§ 15 Abs. 3 EStG) is relevant for practices operating as partnerships (Personengesellschaften): a single commercial activity can "infect" the entire partnership income, converting all income from freelance (freiberuflich) to commercial (gewerblich) with trade tax (Gewerbesteuer) consequences.

Scope in this IG: The profiles in this IG operate at the invoice / billing level and do not model income-tax classification. The Abfärbetheorie is documented here as context for implementers building practice management systems that need to:

1. Track whether a practice entity is a Freiberufler ( 18 EStG) or Gewerbetreibender ( 15 EStG)
2. Flag invoices that originate from potentially commercial activities (e.g. sale of products, laboratory mark-ups)

The BillingTypeCS codes (igel, bg, hzv) can serve as a starting point for classifying activities — implementers must apply appropriate legal review for their specific entity structure.

ZUGFeRD / XRechnung Mapping

The TaxCategoryDE ValueSet uses UNECE-5305 codes (urn:un:unece:uncefact:codelist:standard:5305) which correspond directly to the EN 16931 / ZUGFeRD / XRechnung BT-151 (Seller tax category code). The local TaxCategoryCS was removed in v0.54.0 — the UNECE URN is now the authoritative system:

FHIR system URI: urn:un:unece:uncefact:codelist:standard:5305
ZUGFeRD XML path: ram:ApplicableTradeTax/ram:CategoryCode
XRechnung XML path: cac:TaxCategory/cbc:ID

Migration note: Systems that previously used the local TaxCategoryCS (https://fhir.cognovis.de/praxis/CodeSystem/tax-category-de) must migrate to the UNECE URN. The code values (S, AA, E, AE, Z) remain unchanged.

For ZUGFeRD MINIMUM profile (used in B2G, XRechnung): only codes S and E are valid — include AE and Z only in EN16931 or EXTENDED profiles.

Out of Scope: Vorsteueraufteilung

Vorsteueraufteilung (input VAT apportionment, § 15 Abs. 4 UStG) — the pro-rata allocation of input VAT between deductible (for taxable services) and non-deductible (for exempt services) — is out of scope for this Implementation Guide.

Reasons:

• Vorsteueraufteilung requires knowledge of the overall revenue split across a fiscal year, which is an accounting-system concern, not a per-transaction FHIR billing concern.
• The calculation method (Umsatzschlüssel, Flächenschlüssel, etc.) varies by practice type and must be agreed with the practice's tax advisor.
• FHIR resources (Invoice, ChargeItem) capture the gross/net amounts per service — the aggregation and apportionment logic belongs in the downstream accounting system (e.g. DATEV).

Implementers requiring Vorsteueraufteilung should use the Invoice.totalNet / Invoice.totalGross values and the ext-tax-category codes to feed their accounting system's apportionment logic.

Disclaimer

This documentation is for technical implementers of FHIR-based practice management systems. It does not constitute legal or tax advice.

Tax law (UStG, EStG, StrlSchG) is subject to change. The thresholds, rates, and exemption rules described here reflect the legal situation as of the IG publication date. Always verify the current legal requirements with a qualified tax advisor (Steuerberater) before implementing billing workflows.

The FHIR profiles in this IG provide the data model for capturing tax-relevant information — compliance with German tax law remains the responsibility of the practice management software and its operators.