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Send Lexware Office payment reminders for overdue invoices

Overdue invoices pile up in the Belege list in orange, and sending each reminder means opening the invoice, adding the fee, checking the text and sending it, so it waits until the end of the month.

Cotlet does it in your own Lexware Office (lexoffice) account with list_documents, get_document and send_payment_reminder, called by your AI agent, an n8n workflow or a script.

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Hosted · nothing to install or maintain

Can Lexware Office (lexoffice) do this on its own?

Lexware Office has the Mahnen action in the app, which prepares one reminder per invoice (checked 14 Oct 2026). Its public API, available from version XL, has no endpoint for reminders and no way to send a document by email. Nothing in Lexware Office sends reminders on a schedule or by a rule such as days overdue.

How you do it in Lexware Office (lexoffice) today

  1. Open Belege in the main menu and check Überfällige or Offene Belege in the left navigation; overdue documents are marked in orange in every list.
  2. Click the invoice, open Weitere Aktionen (the three dots) and choose Mahnen, which only works for invoices created in Lexware Office, not imported ones.
  3. Adjust the document title and introductory text, load a saved text template if you use one, and add a fee with + Artikel by picking the item type Mahngebühr.
  4. Click Vorschau to check the document, then Speichern and Versenden to send it by email or post.
  5. Open the invoice later and scroll to the Mahnungen section in the details to see which reminders already went out.

How to send Lexware Office payment reminders for overdue invoices

Prompt

Every Monday, list the overdue invoices in Lexware Office. For invoices more than 14 days overdue, send a payment reminder with a 5 EUR fee. Show me the others with the days overdue and do not touch them.
  1. 01

    Pull the overdue list

    Your agent calls list_documents with type invoice and status overdue and pages through the cursor, so the whole backlog is judged in one run, not only the first page.

  2. 02

    Read each invoice before acting

    get_document returns the open amount, the due date and the Mahnungen already sent. An invoice that has a reminder from the last seven days is skipped, so nobody gets two mails in a week.

  3. 03

    Apply your rule

    Invoices past the number of days in your prompt go to the reminder pile, with the fee you named. Anything younger, or any invoice to a customer you listed as a key account, is only reported.

  4. 04

    Send the reminder

    send_payment_reminder opens Mahnen on the invoice, uses your saved text template, adds the Mahngebühr line and sends by email. It asks for your OK per call by default, because the customer receives it.

  5. 05

    Report what moved

    The agent lists each reminder sent with the amount and days overdue, and each invoice it left alone with the reason. Imported invoices that Mahnen cannot handle are listed separately.

What you get back

Example data

Overdue invoices: 7
Reminders sent 3:
- RE1031 Nordlicht Design GmbH, 1,130.50 EUR, 21 days overdue, fee 5.00 EUR
- RE1034 Becker Consulting, 2,380.00 EUR, 18 days overdue, fee 5.00 EUR
- RE1036 Studio Fjord, 595.00 EUR, 16 days overdue, fee 5.00 EUR
Left for you 4: 2 under 14 days overdue, 1 reminded last Thursday, 1 imported invoice

Other ways to ask

  • Send a friendly Zahlungserinnerung at 7 days overdue and a Mahnung with a fee at 21 days, using my saved texts.
  • List overdue invoices over 1,000 EUR with the customer's contact person, but do not send anything.
  • Every Friday, remind customers whose invoice is more than 10 days overdue and email me the list afterwards.

What Lexware Office (lexoffice) allows, and what to know first

  • Lexware Office shows the Mahnen action only for invoices created in Lexware Office, not for imported ones.
  • The reminder email contains a link to the reminder, and that link does not update when the customer pays later, so Lexware advises resending the paid invoice then.
  • Lexware Office stores reminders inside the invoice: they appear in the Mahnungen section of its details and are not separate documents.
  • A reminder fee is added as an item of type Mahngebühr, and the total updates automatically.
  • Overdue documents are marked with orange text in all overview lists, and Überfällige is its own filter under Belege.

send_payment_reminder asks for your OK by default. To run it weekly without you, switch confirmation off for that tool in your dashboard.

Sources: Lexware Office Help: Zahlungserinnerungen und Mahnungen erstellen · Lexware Office Help: Rechnungen & Angebote · Lexware Office API documentation

Call send_payment_reminder from a script

curl

curl -X POST https://cotlet.dev/api/v1/lexware-office/documents/d_9c31be/payment-reminders \
  -H "Authorization: Bearer $COTLET_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"fee_amount":5}'

Example response

{
  "document_id": "d_9c31be",
  "number": "RE1031",
  "reminder_number": 1,
  "fee_amount": 5,
  "sent_to": "buchhaltung@nordlicht.example",
  "sent_at": "2026-10-14T08:02:00+02:00"
}

MCP: add https://cotlet.dev/mcp/v1 with the same key; the call is lexware_office_write → send_payment_reminder. Example data.

Schedule it in n8n, Make, Zapier or cron

Lexware Office (lexoffice) tools this automation uses

Cotlet Lexware Office (lexoffice) tools used to send Lexware Office payment reminders for overdue invoices
Tool Parameters
list_documents type, status, contact_id, from_date, limit, cursor
get_document document_id
send_payment_reminder document_id, fee_amount, intro_text
All 14 Lexware Office (lexoffice) tools with descriptions

Frequently asked questions

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