# Payment advice: Doppelzahlung (already-paid invoice)

When a payment advice still lists an already-paid invoice, Cortena books it as Doppelzahlung (DZ) in the avis workflow instead of allocating again.

When a payment advice (Zahlungsavis) still lists an invoice that is **already paid**, Cortena does not allocate that line again as an open receivable. Instead it treats the line as a **double payment (Doppelzahlung)** in the payment-advice workflow, so the avis can still clear in full while the ERP books a DZ contra for the overpayment.

**Who this is for:** AR operators who reconcile payment advices when the avis repeats an invoice that Cortena (or the connected ledger) already shows as paid.

## 1. When Doppelzahlung applies

A line on the payment advice matches a receivable that is already paid (in Cortena and/or the connected accounting / CRM ledger).

Typical situations:

- The customer paid earlier (bank match or previous avis), then the same invoice appears again on a later avis
- The avis includes an invoice that the ledger already cleared
- Partial earlier settlement left the avis line looking “open” while the receivable is already marked paid

Cortena flags those lines as double payment so the rest of the avis workflow can continue without pretending the invoice is still open.

## 2. How it looks on the payment advice

1. Open **Receivables → Payment advices** and select the avis.
2. An already-paid match shows: **Receivable already paid: booked as double payment (DZ)**.
3. A banner may say how many receivables **will be booked separately as double payment (Doppelzahlung)**.

Those lines stay visible on the avis so you can audit why the amounts still add up.

## 3. Booking plan and sync workflow

When you run the payment-advice sync / booking plan, Doppelzahlung is its own group. Typical order:

1. Allocate open invoices
2. Credit-note / remaining handling
3. **DZ contra** lines for already-paid invoices
4. Book / confirm in the connected system when the plan requires it

On the linked bank transaction (or equivalent ERP payment document), Cortena posts a contra line such as **`DZ <invoice>`** so leftover **Available** after normal allocates is soaked correctly.

If “already paid” in Cortena is stale but the ledger still shows an open item, a live recheck can fall back to a normal allocate instead of DZ.

## Tips and limitations

- Doppelzahlung is part of the **payment advice workflow**, not a separate manual booking you invent outside the avis.
- Some plans only persist DZ (with credits/fees) after the final **Book** / confirm step. Cortena runs that at the end of sync when required.
- Related: [Payment advice: Sync to WeClapp](https://help.cortena.ai/guides/advanced/payment-advice-sync-weclapp) (ERP write-back example), [Payment advice: auto-settle](https://help.cortena.ai/guides/advanced/payment-advice-auto-settle), [Open items and payment write-back](https://help.cortena.ai/guides/advanced/open-items-write-back), [Payment advice workspace](https://help.cortena.ai/guides/advanced/payment-advice-workspace).

## Quick reference

| Task | Where |
| --- | --- |
| See DZ lines | Payment advice detail → lines + booking plan |
| Run the workflow | Sync / Confirm on the payment advice |