Invoicing is one of those tasks every company does, and nearly every company does it by hand. You open Szamlazz.hu or Billingo, enter the data, download the PDF, send it by email, then remind yourself to check in two weeks whether it's been paid. If not, you send a reminder. If still not, you call the client. If you handle 50 invoices a month, this easily adds up to 15-20 hours.
This article is about how you can automate this entire process, compatible with Hungarian invoicing systems, taking NAV (Hungarian Tax Authority) online invoicing obligations into account.
Business owners who use Szamlazz.hu or Billingo and are tired of manual invoicing. Webshop owners who issue a separate invoice after every order. Service providers who invoice the same clients for the same amount every month.
The problem: why does invoicing eat up so much time?#
Because it's not a single step. Issuing an invoice itself takes 2-3 minutes. But the full process:
- Data collection: Who's the client? What's the exact line item total? Which VAT rate? What payment deadline?
- Issuance: Logging into the invoicing system, entering data, checking, finalizing the invoice
- Sending: PDF download, writing the email, attaching, sending (or using the invoicing system's built-in send feature)
- Follow-up: Has the client paid? Has the deadline passed? Sending reminders
- Accounting preparation: Recording invoice number, date, amount in the ledger
- NAV reporting: Online invoice data reporting (Szamlazz.hu and Billingo handle this automatically, but if you use a different system, it's an extra step)
Single invoice: 5-10 minutes. 50 invoices a month: 4-8 hours. Add reminders, receivables management, monthly reports. Total: 15-25 hours per month.
What automation scenarios exist?#
Below we present 5 typical scenarios that we regularly build for Hungarian SMBs.
1. Automatic invoice issuance on webshop orders#
This is the most common need for webshop operators. When a customer places an order and pays, the invoice is automatically issued and sent.
How it works:
- The webshop (Shoprenter, WooCommerce, Shopify) notifies Make.com or n8n via webhook
- The automation creates the invoice in Szamlazz.hu or Billingo (via API)
- The finished invoice is attached as a PDF to the notification email
- Invoice data is entered into the accounting ledger (Airtable, Google Sheets)
At the Mindwell webshop, we use exactly this solution: from order receipt to invoice delivery, everything is automatic, without human intervention. We described the details in the order management case study.
2. Recurring billing#
If you invoice the same client the same amount on a monthly basis, this process can be fully automated.
How it works:
- You maintain a table of recurring invoices in Airtable or Google Sheets: client, amount, frequency, next billing date
- At the beginning of each month (or on the set date), the workflow goes through the list
- Issues the invoice, sends it by email, and sets the next date
- If the payment method is bank transfer, the workflow monitors the bank account and automatically closes the invoice upon receipt
Savings: If you have 20 recurring invoices per month, that's 2-3 hours of manual work. Automated: 0 minutes.
3. Automatic payment reminders#
This is one of the quickest automations to implement, with an immediately measurable impact.
How it works:
- The workflow checks open invoices daily
- 3 days before the deadline: polite reminder ("Your invoice is due soon")
- On the deadline day: firm notification ("The payment deadline is today")
- 7 days past the deadline: first notice ("The invoice is overdue, please settle it soon")
- 14 days past the deadline: second notice, more serious tone
- 30 days past the deadline: notification to company management that manual intervention is needed
Every email is templated but personalized (client name, invoice number, amount, due date). The tone escalates gradually but remains professional throughout.
Most late payments aren't due to bad faith, but forgetfulness. The client simply forgot. An automatic reminder 3 days before the deadline is usually enough for them to pay on time. Our experience is that after implementing automatic reminders, the number of late payments drops by 25-40% in the first month.
4. Automatic processing of incoming invoices#
This isn't about outgoing invoices, but handling incoming ones. If you regularly receive invoices from suppliers, subcontractors, and service providers, this can also be automated.
In the Murabau Kft. project, we built a system for processing incoming invoices using Mistral AI OCR. The employee uploads the PDF, the AI extracts the data (issuer, amount, line items, payment deadline), and automatically records it in the ledger. Processing time dropped from 5-10 minutes to less than 1 minute per document.
We described the technical details in the AI OCR invoice processing article.
5. Monthly financial report#
An automatic end-of-month summary of issued invoices, received payments, outstanding receivables, and expenses.
How it works:
- On the last day of the month, the workflow collects data from the invoicing system, bank account, and ledger
- Generates a summary report: revenue, expenses, receivables, TOP 10 clients, payment rate
- Sends it by email to company management and the accountant
- If there's an anomaly (e.g., revenue is 20% lower than the previous month), it flags it with a special alert
API capabilities of Hungarian invoicing systems#
The good news is that the two largest Hungarian online invoicing platforms both have APIs that automation tools can easily work with.
Szamlazz.hu API#
The Szamlazz.hu API is one of the best-documented Hungarian APIs. It supports invoice creation, modification, cancellation, payment status management, and invoice queries. Make.com has a dedicated Szamlazz.hu module, so you can plug it into your automation with drag-and-drop.
What you can automate:
- Invoice issuance (proforma, standard, final invoice)
- Invoice email delivery
- Payment status queries
- Invoice cancellation
- Fee request issuance
NAV online invoice data reporting happens automatically through Szamlazz.hu, so you don't need to handle it separately.
Billingo API#
The Billingo API is also comprehensive: invoices, partners, products, and payment methods can all be managed through it. Make.com has a Billingo module too, and in n8n it's easily used with the HTTP node.
What you can automate:
- Invoice issuance in all types
- Partner data management (create, update)
- Recurring billing
- Payment status updates
- Invoice export (PDF, XML)
NAV Online Invoice#
NAV online invoice data reporting has been mandatory since 2020 for all domestic invoices with VAT content above 100,000 HUF (and since 2024, for VAT-exempt invoices too). If you use Szamlazz.hu or Billingo, this happens automatically. But if you invoice from a different system (e.g., SAP, custom software), or if you want to use NAV data for processing incoming invoices, the API is directly accessible.
The NAV Online Invoice system can not only receive invoice reports, but also query them. This means you can automatically verify whether a partner actually issued the invoice you received. You can also use incoming invoice data (reported to NAV by the partner) for automatic accounting preparation.
Technical architecture#
Let's look at what a typical invoicing automation looks like in practice.
Trigger: what initiates invoicing?
The trigger can be:
- Webhook from the webshop (new order, successful payment)
- Form submission (e.g., order form on the website)
- Schedule (every 1st of the month for recurring invoices)
- Manual trigger (a button press in Airtable or the CRM)
- Incoming email (the system detects an invoice arrived as an attachment)
Most companies have 2-3 triggers running simultaneously, as different invoicing scenarios operate in parallel.
Data collection and validation
The workflow collects the invoice data:
- Client data (name, address, tax number) from the CRM or Airtable
- Items, quantities, unit prices from the order or service agreement
- VAT rate, payment method, payment deadline from settings
Important: It's worth having the workflow validate the data before the invoice is issued. Missing tax number, invalid address, zero amount: these errors should be caught automatically. If something doesn't check out, the workflow should notify the responsible colleague instead of issuing a faulty invoice.
Invoice issuance via API
With the validated data, the workflow calls the Szamlazz.hu or Billingo API and issues the invoice. The response contains the invoice number and the PDF download link.
The issued invoice data is automatically entered into the ledger: invoice number, date, amount, partner, payment deadline, status.
Delivery and follow-up
The system automatically sends the invoice by email (either through the invoicing system's built-in send feature, or via custom email if you want to customize the text).
From this point, follow-up is also automatic: the workflow monitors the payment deadline and sends reminders according to the schedule described above.
Real example: the Murabau case#
Murabau Kft. is a construction company where 60-80 incoming documents were handled manually each month: invoices, completion certificates, delivery notes. Processing took 5-10 minutes per document, with a monthly error rate of 4-5 typos.
With the AI OCR system, we reduced processing time to under 1 minute per document, and monthly admin time dropped from 8 hours to 30 minutes. Recognition accuracy is above 95%, and uncertain data is flagged for review.
The solution wasn't limited to incoming invoices: we also automated outgoing invoicing. After a completion certificate is approved, the system automatically issues the partial invoice in Billingo with the correct line items and amounts.
If you have similar construction or document processing needs, we described the technical solution in detail in the AI OCR article.
How much does invoicing automation cost?#
| Component | Cost |
|---|---|
| Szamlazz.hu / Billingo subscription | Existing (no extra needed) |
| Make.com (automation) | $9-29/month |
| Airtable (ledger) | $0-20/month |
| Email sending (Resend / AWS SES) | $0-5/month |
| Software total | $9-54/month (~4,000-22,000 HUF) |
| Implementation (with an expert) | 150,000-400,000 HUF (one-time) |
The ROI is fast. If you save 15 hours a month on invoicing, and your hourly cost (employer gross) is 4,000 HUF, that's 60,000 HUF in monthly savings. Software cost is 4,000-22,000 HUF/month. The implementation pays for itself in 2-4 months. Add to that the reduced error rate and fewer late payments.
If you're just starting with invoicing automation, we recommend this order:
- Payment reminders - this is the easiest, and the impact is immediate (fewer late payments)
- Recurring invoices - if you have monthly invoices, automate these second
- Webshop invoicing - if you have a webshop, this is the next logical step
- Incoming invoice processing - the most technical, but the biggest time savings
In the business process automation guide, we described the full implementation process, from prioritization to ROI calculation. In the 5 processes any SMB can automate article, we also cover automation in 4 other areas beyond invoicing.
The 4 most common invoicing automation mistakes#
1. No error handling#
What happens if the Szamlazz.hu API is down? If the client's data is incomplete? If the invoicing system rejects the request? Without error handling, the invoice isn't created, and you don't know about it. Every workflow should have at least a "if something fails, send an email notification" branch.
2. Not testing with real data#
Everything works in the test environment, but in production you discover that some clients are missing their tax number, or a product has no VAT rate. Test with real data and fix errors before going full production.
3. Forgetting about NAV reporting#
If you don't use Szamlazz.hu or Billingo (but e.g., a custom system), you need to handle NAV online invoice reporting separately. This isn't optional: NAV can impose fines if reporting is missing or late.
4. Not involving the accountant#
Your accountant is the one who works with the data. If the automation produces data in a format or structure the accountant can't use, part of the savings is lost. Coordinate with your accountant on what data they need, in what format, and at what frequency.
Summary#
Invoicing automation isn't rocket science. The APIs of Hungarian invoicing systems (Szamlazz.hu, Billingo) are mature, automation tools (Make.com, n8n) support them with dedicated modules, and implementation typically takes 1-2 weeks.
The key takeaways:
- Start with payment reminders. The smallest investment with the biggest immediate impact.
- Automate recurring invoices. If you issue the same invoices every month, this can be solved in minutes.
- Think about incoming invoices too. Automating outgoing invoices is the obvious first step, but processing incoming invoices also saves significant time.
- Build error handling into every workflow. Invoicing is the area where a mistake costs money.
- Involve your accountant. The best automation is one that makes your accountant's life easier too.
If you'd like to automate your company's invoicing, as part of our business automation service we'll assess your current processes, select the best tools, and get the system running within 2 weeks.