Accounting Boundary & DATEV Strategy

Busflow is not a general ledger and does not replace DATEV, Agenda, Lexware, or the operator's Steuerberater. Busflow owns the travel-domain sub-ledger: the classified economic facts that arise from bookings, deposits, cancellations, supplier costs, onboard sales, invoices, and trip execution. DATEV and the Steuerberater own legal custody, bookkeeping finalization, balance sheet work, and communication with tax authorities.

The product promise is not "Busflow does accounting." The product promise is: Busflow gives the accountant better classified facts than a generic booking export can.

Boundary

Layer	Busflow owns	DATEV / Steuerberater owns
Operational truth	Bookings, passengers, payments, cancellations, supplier costs, onboard sales, route/country/service context	Bank/accounting reconciliation review, bookkeeping controls
Semantic classification	TRAVEL_REVENUE, CANCELLATION_FEE, SUPPLIER_REFUND, ONBOARD_SALE, STANDARD_VAT, MARGIN_SCHEME_25, geography and service-type buckets	Professional judgment, chart-of-accounts mapping review, corrections when policy/legal interpretation differs
Sub-ledger output	FinancialLedger, TaxLedgerEntry, invoice/credit-note snapshots, classified export rows, audit trail	General ledger posting, DATEV import/use, BWA/SuSa, VAT return process
Legal custody	Evidence package and traceable pre-ledger records	Official accounting records, balance sheet, direct tax authority communication

Busflow must preserve the meaning of money before export. A row saying "1,150 EUR revenue" is not enough if the domain history says "1,000 EUR delivered travel service + 150 EUR retained cancellation amount." DATEV can process booking records and digital documents, but it cannot infer travel-domain semantics that Busflow flattened away before export.

In Scope

• Maintain a classified travel sub-ledger from domain events and immutable facts.
• Preserve original price snapshots, policy versions, cancellation facts, supplier/service classifications, and geography buckets.
• Generate tax/margin working records such as TaxLedgerEntry from classified facts, not only from scalar revenue totals.
• Export DATEV-ready records with enough context for the Steuerberater to review, post, correct, or override.
• Import DATEV/BWA/SuSa outputs for reconciliation and management reporting.

Out of Scope

• Running a native general ledger.
• Replacing DATEV or the Steuerberater.
• Filing tax returns directly with ELSTER or tax authorities.
• Owning final legal interpretation when the Steuerberater classifies a case differently.
• Treating DATEV export formatting, account mapping, or CSV/API plumbing as F&E.

USP

Generic tools can export invoices, payments, and receipts. Busflow's advantage is domain classification before export:

• It knows whether money came from delivered travel service, retained cancellation fee, ancillary, onboard sale, or refund.
• It knows whether costs are Eigenleistung or Fremdleistung.
• It knows whether procurement belongs to EU or Drittland portions.
• It knows which PriceMatrix, cancellation policy, and tax-rule version applied when the fact occurred.
• It can explain a DATEV export row back to the booking, passenger, supplier cost, cancellation, invoice, and ledger state that produced it.

This is why deferring accounting execution to DATEV does not remove the need for Busflow's tax/margin sub-ledger. DATEV receives the classified result; Busflow produces and explains the classified result.

Funding Boundary

For BSFZ/F&E framing, the distinction is strict:

• Potential F&E: The mechanism that folds incomplete, versioned, classified travel facts into path-independent, audit-safe tax/margin states under non-linear rules and later corrections.
• Standard engineering: DATEV export formatting, BU/account mapping, API integration, CSV generation, invoice rendering, and routine validation.

If Busflow exported only raw payments and Belege and left all semantic classification to the Steuerberater in DATEV, the tax/margin F&E claim would shrink sharply. The intended product strategy is different: Busflow exports classified economic facts and lets DATEV/Steuerberater perform accounting custody and final professional review.