What connects to Shopware

Shopware is a widely used shop system in Germany, and a single instance often runs several sales channels and currencies at once. It knows the basket, the customer and their billing country, the payment method, and the shipping, and it generates invoice and credit-note documents itself.

That puts Shopware upstream of two kinds of systems. An ERP receives orders as sales documents against the right business partner and items, and sends item master data, price lists, and warehouse stock back, as in Shopware to SAP Business One. Accounting receives the documents as bookings, either straight into the Kanzlei’s DATEV, as in Shopware to DATEV, or into an accounting tool first, as in Shopware to sevDesk.

Where Shopware integrations break

The order is not the audit record. A Shopware order can be edited after the fact; the invoice document it generated carries the sequential Belegnummer. Book the order instead and the number range gets gaps your tax advisor will flag.
Cancellation and credit note are different documents. Shopware treats them as distinct document types, and each needs its own booking logic. A partial credit note reverses the original’s accounts and tax treatment on its own date, and never edits or deletes the original.
Shopware stores tax amounts, not tax keys. It records the calculated tax and the customer country. The DATEV tax key, the sevDesk tax type, or the SAP tax code has to be derived from both, not copied from the percentage.
Two systems want the number range. Shopware and the accounting side both assign invoice numbers. Decide the owner up front, and never force a document number into SAP.
One instance, many channels and currencies. Each sales channel may post to its own revenue account or cost centre, and foreign-currency orders need a defined conversion and rounding rule so the batch balances.