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Key takeaways
- Verify the legal supplier before matching account numbers.
- Save the agreed destination for later exports.
- A mapping change does not repair a package already imported.
- Check the actual receiving ledger before accepting the handoff.
Same supplier, two numbers
A fictional supplier is already account 70042 in DATEV. Hans has independently created the same verified supplier as 70088. The numbers are examples, not recommended account assignments.
| Before | Agreed mapping | Result to check |
|---|---|---|
| Same supplier, two numbers | Hans supplier → DATEV 70042 | Export preview shows the agreed account |
| New €357 invoice | Use that mapping | Invoice arrives under the existing supplier |
| Related €357 payment | Keep its allocation | No duplicate invoice, supplier or bank movement |
Once the mapping is saved, later exports can reuse it. The firm does not need to renumber the same relationship each month. The configured package includes required supplier/customer master-data additions where applicable.
A similar name is not enough
Check the invoice issuer and available legal identifiers against the firm's master record. One brand may invoice through several entities. Conversely, a spelling change may still refer to the same supplier.
If 70042 belongs to a different legal entity, do not reuse it for convenience. Resolve the collision with the firm. A shared payment-collection account is also not proof that two suppliers are identical.
Read same brand, different legal supplier when the identity itself is unclear.
Correct the mapping at the right stage
| Package state | What to do |
|---|---|
| Not exported | Save the corrected mapping and inspect the preview |
| Exported, not imported | Identify the superseded file and use the agreed replacement |
| Already imported | Coordinate the correction in the receiving books; prevent a duplicate import |
Changing a future export mapping does not rewrite posted history or an older package. DATEV's booking-batch specification describes the file format; the firm still checks the actual import in its own environment.
Keep balances separate from invoice detail
A €2,400 supplier opening balance preserves a starting amount. It does not show whether that amount came from two invoices, a credit or partial payments. Later invoice-level allocations may need records from the existing archive.
Agree the cutover date, imported balance scope and location of the historical detail. Do not promise a complete OPOS history from an aggregate balance import.
A small first-month test
Use one existing supplier, one genuinely new supplier and one deliberate numbering conflict. After import, check the identities, invoice amounts and bank movements. Include a payment against an earlier balance if that occurs in the client's real work.
Hans's benefit is continuity: new monthly work can follow established supplier identities, with corrections saved for reuse. The acceptance check remains with the firm. The DATEV setup guide explains the wider first-month plan.
Sources
Sources were checked on 27 September 2026. This article provides orientation and is not tax, legal, or accounting advice.
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