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Send SnelStart payment reminders for overdue invoices with AI

Overdue invoices sit in the invoice overview until someone opens each one and clicks Herinnering. In a busy week that is the job that slips.

Cotlet does it in your own SnelStart account with list_sales_invoices, get_sales_invoice and send_invoice_reminder, called by your AI agent, an n8n workflow or a script.

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Hosted · nothing to install or maintain

Can SnelStart do this on its own?

SnelStart Web has a Herinnering button per invoice (checked 14 Oct 2026), from the inStap package. The fuller process with aanmaningen as dossiers needs inBalans in SnelStart 12. The B2B API is gated and has no official MCP server, so no agent can call a reminder without your own certified integration.

How you do it in SnelStart today

  1. Open Facturen in SnelStart Web and go to Factuuroverzicht.
  2. Filter the overview on vervallen (overdue) to see the late invoices.
  3. Click an invoice line to open the invoice.
  4. Click Herinnering. SnelStart emails the customer that an invoice is open and sends the invoice again with the reminder text.
  5. Repeat for each late invoice. Nothing in the overview shows which ones you already reminded.

How to send SnelStart payment reminders for overdue invoices with AI

Prompt

List my overdue sales invoices in SnelStart and show me who is late and by how many days. After I say OK, send the standard reminder for each one.
  1. 01

    Pull the overdue list

    list_sales_invoices filters on vervallen, the same filter the overview offers, and returns amount, due date and customer for each invoice.

  2. 02

    Skip the ones SnelStart refuses

    The Herinnering button works for a regular invoice only, so the agent skips e-invoices and lists them for you to chase another way.

  3. 03

    Check each customer

    get_sales_invoice reads the customer and the email address the reminder will go to. Invoices without an address are held and reported.

  4. 04

    Remind after your OK

    send_invoice_reminder sends the reminder email per invoice. It reaches your customer, so it waits for your confirmation unless you switched that off.

  5. 05

    Keep a record

    The agent reports which invoices got a reminder today. SnelStart itself does not show that in the overview, so the report is your log.

What you get back

Example data

Overdue invoices: 4
- 2026-0388 Bakker Logistics, 760.00, due 26 Sep: reminder sent
- 2026-0391 Van Dijk Design, 475.00, due 30 Sep: reminder sent
- 2026-0377 De Wit Advies, 1,210.00, due 12 Sep: held, e-invoice
- 2026-0395 Studio Zuid, 320.00, due 4 Oct: held, no email address
Reminders sent: 2

Other ways to ask

  • List the overdue invoices and their total but send nothing.
  • Remind only invoices that are more than 14 days late.
  • Every Monday, send reminders for overdue invoices below 1,000 and list the larger ones for me.
  • Show me which overdue invoices have a customer with no email address on the card.

What SnelStart allows, and what to know first

  • The Herinnering option is described for the inStap package in SnelStart Web.
  • The reminder button cannot send a reminder for an e-invoice.
  • The reminder email tells the customer that an invoice is still open and sends the invoice again.
  • Extended reminders and aanmaningen as dossiers are an inBalans process in SnelStart 12, not in SnelStart Web.
  • The invoice overview filters on alles, concept, vervallen, openstaand and betaald.

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

Sources: SnelStart Web help: Een herinnering versturen vanuit SnelStart Web · SnelStart Web help: Een factuur maken in SnelStart Web (overview filters)

Call send_invoice_reminder from a script

curl

curl -X POST https://cotlet.dev/api/v1/snelstart/invoices/inv_2026_0388/reminder \
  -H "Authorization: Bearer $COTLET_API_KEY"

Example response

{
  "invoice_id": "inv_2026_0388",
  "number": "2026-0388",
  "reminder_sent_to": "ap@bakker.example",
  "sent_at": "2026-10-14T09:12:00+02:00"
}

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

Schedule it in n8n, Make, Zapier or cron

SnelStart tools this automation uses

Cotlet SnelStart tools used to send SnelStart payment reminders for overdue invoices with AI
Tool Parameters
list_sales_invoices status, customer_id, limit, cursor
get_sales_invoice invoice_id
send_invoice_reminder invoice_id
All 14 SnelStart tools with descriptions

Frequently asked questions

Is it safe to connect SnelStart to Cotlet?

Yes. You sign in to SnelStart yourself, in your own Cloud Browser in the EU, and we never save your password. Your agents only get SnelStart once you enable it, every background request is listed, and the browser profile is stored encrypted with AES-256-GCM, the cipher 1Password uses for its vaults. The AI model never sees a login, posts and messages wait for your OK, and Disable for agents cuts access in one click. Independent scanners grade cotlet.dev A+ on Qualys SSL Labs, securityheaders.com and Mozilla Observatory; live results are on https://cotlet.dev/security.

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