Számlázz.hu automation

Cancel a Számlázz.hu invoice with a storno invoice

A numbered Számlázz.hu invoice cannot be deleted. When an order is a duplicate or a price is wrong, you cancel it with a storno invoice, and the reason has to be written in by hand.

Cotlet does it in your own Számlázz.hu account with get_invoice and cancel_invoice, called by your AI agent, an n8n workflow or a script.

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Hosted · nothing to install or maintain

Can Számlázz.hu do this on its own?

The Számla Agent API can reverse an invoice by sending one XML message (checked 14 Oct 2026). It is an extra-cost add-on, it needs an Agent key, and the message has a fixed field order. The web interface does the same through Sztornó számla.

How you do it in Számlázz.hu today

  1. Go to Számla / Kimenő számláim.
  2. Click the three dots at the end of the invoice row.
  3. Click Sztornó számla.
  4. Enter the reason for the storno; Számlázz.hu adds it to the storno invoice automatically.
  5. Check that the storno invoice carries the same delivery date as the original, as the knowledge base requires, and download the credit details as a CSV if the original had a jóváírás.

How to cancel a Számlázz.hu invoice with a storno invoice

Prompt

Cancel invoice ABC-2026-00131 in Számlázz.hu with a storno invoice. The reason is a duplicate order. Show me the invoice details and ask me before you cancel.
  1. 01

    Read the invoice first

    Your agent calls get_invoice and shows the buyer, items, gross total, delivery date and payments, so you cancel the invoice you meant and not a neighbour with a similar number.

  2. 02

    Refuse what is already cancelled

    If the invoice is itself a storno, or already has a storno against it, the agent says so and stops instead of stacking a second reversal.

  3. 03

    Write the reason

    The reason comes from your prompt, for example duplicate order. The agent passes it to cancel_invoice so it lands on the storno invoice.

  4. 04

    Wait for your confirmation

    cancel_invoice creates a legal document that goes to NAV, so the call waits for your OK. Until you switch confirmation off for this tool, nothing is cancelled without it.

  5. 05

    Report the new document

    The agent gives you the storno invoice number, the original it reverses and the amounts, and reminds you to issue a corrected invoice if the order still stands.

What you get back

Example data

Cancelled: ABC-2026-00131 (Blue Fern Studio Kft., 127,000 HUF gross)
Storno invoice: ABC-2026-00149
Reason on the document: duplicate order
Delivery date: same as the original, 2026-10-08
Next: issue a new invoice if the order still stands

Other ways to ask

  • Cancel invoice ABC-2026-00131 and issue a corrected one for 2 x Website retainer instead of 3.
  • Find the invoices for Blue Fern Studio Kft. from this month and tell me which ones look like duplicates. Do not cancel anything.
  • Cancel these three invoice numbers with the reason wrong customer, one confirmation at a time.

What Számlázz.hu allows, and what to know first

  • An invoice with a number cannot be deleted in Számlázz.hu. It has to be corrected or cancelled, because its data may already have been reported to the authorities.
  • The storno invoice must carry the same delivery date as the original invoice.
  • The reason you enter is added to the storno invoice automatically.
  • NAV accepts a storno only if the original invoice was submitted successfully, so a storno of a rejected invoice can fail.
  • The knowledge base has separate articles for a storno made by mistake and for a storno with a wrong delivery date.

cancel_invoice asks for your OK by default. To run it on a schedule without you, switch confirmation off for that tool in your dashboard.

Sources: Számlázz.hu knowledge base: Cancelling an invoice (Számla sztornózása) · Számlázz.hu knowledge base: What if I cancelled an invoice by mistake? · Számla Agent: Reversing invoice

Call cancel_invoice from a script

curl

curl -X POST https://cotlet.dev/api/v1/szamlazz-hu/invoices/ABC-2026-00131/cancel \
  -H "Authorization: Bearer $COTLET_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"reason":"Duplicate order"}'

Example response

{
  "storno_invoice_number": "ABC-2026-00149",
  "original_invoice_number": "ABC-2026-00131",
  "reason": "Duplicate order",
  "gross": -127000,
  "currency": "HUF"
}

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

Schedule it in n8n, Make, Zapier or cron

Számlázz.hu tools this automation uses

Cotlet Számlázz.hu tools used to cancel a Számlázz.hu invoice with a storno invoice
Tool Parameters
get_invoice invoice_number
cancel_invoice invoice_number, reason
All 8 Számlázz.hu tools with descriptions

Frequently asked questions

Can I undo a storno?

The knowledge base has an article for a storno made by mistake, so it is handled in the app, not by deleting the storno invoice. Check that article before you confirm a call.

Is it safe to connect Számlázz.hu to Cotlet?

Yes. You sign in to Számlázz.hu yourself, in your own Cloud Browser in the EU, and we never save your password. Your agents only get Számlázz.hu 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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