Auto-Filling Counterparty Data from a NIP (GUS) — No More Manual Typing

In short: Instead of copying a counterparty's name, address, and REGON (business registry number) from an invoice, you enter just the NIP (tax ID), and the company data fills in automatically from the GUS (Central Statistical Office) registry — the REGON database. That means fewer typos, faster invoicing, and a consistent counterparty record. In the same step you can also check the company on the VAT white list (Biała lista), so you get everything at once: correct data and a confirmed bank account before you issue a document or order a transfer.

Adding a new counterparty is usually the same tedious routine: type in the name, watch out for the legal form, enter the address, and hunt down the REGON number somewhere. For one company it's a minor task; for a dozen or so a month, it's real time and a real risk of mistakes. And a typo in the name or a wrong NIP can spoil an invoice and create a mismatch in the JPK (Standard Audit File). This article shows where company data comes from, how auto-filling from a NIP works, and why it's worth pairing it with counterparty verification.

Table of Contents

1. Why manual data entry is a problem
2. Where the data comes from — GUS, REGON, and VIES
3. How auto-filling from a NIP works
4. NIP data and the VAT white list in one step
5. Benefits: fewer errors, faster, a consistent record
6. How to use auto-fill in eKsięgowy AI
7. Limitations — data is only as current as the registry
8. FAQ

1. Why manual data entry is a problem

Manually entering counterparty data looks harmless, but it stacks up several kinds of risk at once:

• Typos in the name and address — "Sp. z o. o." instead of "sp. z o.o.", a missing letter in the street name, the wrong city. The invoice still "looks fine," yet it contains an error.
• A wrong NIP — swap two digits and the payment or document ends up with the wrong entity. This is the most common source of discrepancies in settlements.
• An inconsistent record — the same counterparty entered three times, in three variants of the name. Reports and summaries stop adding up.
• Discrepancies in the JPK — buyer and seller data from invoices flow into JPK files. If the NIP or name is wrong, a mismatch is easy to create — and then you have to correct it.

On top of that there's the plain cost of time. Every new counterparty entry means a few minutes of searching for and copying data from an invoice, an email, or the company's website. Auto-filling from a NIP eliminates that step almost entirely.

2. Where the data comes from — GUS, REGON, and VIES

Company data isn't "guessed" — it comes from official registries.

• GUS / the REGON database. The Central Statistical Office (Główny Urząd Statystyczny, GUS) maintains the REGON register, where every business entity has, among other things, a full company name, registered address, REGON number, and NIP on file. This is the registry data is pulled from once you enter a Polish company's NIP.
• The VAT white list (Biała lista, Ministry of Finance). It rounds out the picture with the counterparty's VAT taxpayer status (active / exempt) and the account numbers reported to the tax office. We cover the register itself in more detail in VAT White List — How to Check a Counterparty.
• VIES (for EU counterparties). For foreign companies from the European Union, data and EU VAT status are confirmed through the VIES (VAT Information Exchange System) using a VAT number with a country prefix (e.g., DE, CZ). This is a separate source from the domestic REGON register.

In short: REGON answers "who the company is" (name, address, identifiers), while the white list and VIES answer "whether it's an active taxpayer and which account to pay into."

3. How auto-filling from a NIP works

The mechanism is simple and comes down to a single input field — the NIP.

1. You enter the counterparty's NIP (10 digits).
2. The system queries the GUS registry for the entity under that number.
3. The record's fields fill in automatically with data from the registry.
4. You verify and save — you have a ready-made counterparty without any manual typing.

What specifically usually gets filled in from just the NIP:

The result: from a single piece of information (the NIP), you get a complete counterparty record, ready for issuing an invoice.

4. NIP data and the VAT white list in one step

The greatest value comes from combining two actions that are normally done separately:

• filling in identifying data (name, address, REGON) from the GUS registry,
• verifying the counterparty on the VAT white list (taxpayer status and account number).

Doing this together, a single NIP query gets you everything you need both to issue a correct invoice and to make a safe payment. This matters especially for larger transactions — as a reminder, for B2B payments above PLN 15,000 gross, paying into an account outside the white list risks losing the tax-deductible cost and incurring joint-and-several VAT liability. We cover the details in VAT White List — How to Check a Counterparty.

So instead of "type in the data manually → then separately paste the NIP into the government search tool → then check the account," you get one step that handles everything.

5. Benefits: fewer errors, faster, a consistent record

• Fewer errors. The data comes from the registry, not from manual typing — typos in the name and address, and mistakes in the NIP/REGON, disappear.
• Faster. Instead of several minutes per counterparty — a few seconds. With a dozen or so new companies a month, the difference is noticeable.
• A consistent record. One correct version of the name and address for every counterparty. Summaries and reports add up, and there are no duplicates.
• Accurate invoices and JPK filings. Buyer data that matches the registry means less risk of discrepancies in JPK files and fewer corrections.
• Due diligence. Verifying a counterparty "along the way" while entering their data is a good, repeatable practice — with no extra effort.

6. How to use auto-fill in eKsięgowy AI

In eKsięgowy AI, auto-fill works right in the conversation with the assistant — you don't need to hunt for data in several places.

1. Give the counterparty's NIP in the chat (e.g., "Add a counterparty with NIP 5252445211").
2. The assistant pulls the company's data from the GUS registry — name, address, and REGON.
3. If needed, it checks the company on the VAT white list — taxpayer status and account number.
4. You confirm — the counterparty is ready for invoicing (including e-invoices to KSeF, the National e-Invoice System).

Because the assistant is integrated with wFirma, the completed data lands right where you keep your books, without copying anything between systems. We describe other ways AI takes work off small businesses' plates day to day in How AI Helps Small Business Accounting.

7. Limitations — data is only as current as the registry

Auto-fill is convenient, but it's worth knowing its limits:

• Data quality depends on the registry. If a company hasn't updated its address or name in REGON, the data you pull will reflect the registry's state, not "the truth as of today."
• Short delays after changes. A newly registered company or a recent data change may appear in the registry with some delay.
• The NIP must be correct and active. For a number that doesn't exist or has been deregistered, the registry won't return any data.
• EU companies go through VIES, not REGON. For a foreign counterparty, data is confirmed through the VIES system using an EU VAT number — the scope of information is often narrower than in REGON.
• VAT status and the account change over time. That's why it's worth repeating the white-list check on the day of payment, rather than relying on a check from weeks ago.

Auto-fill takes the tedious typing off your hands, but it's always worth doing a final confirmation of the data — especially the account before a large transfer — at the moment of the transaction.

Automate your counterparty records with eKsięgowy AI

No more copying names and addresses from invoices. eKsięgowy AI is an AI assistant integrated with wFirma that auto-fills company data from a NIP using the GUS registry, verifies counterparties on the VAT white list, and then issues e-invoices to KSeF. In the same conversation you can also post a receipt from a photo thanks to OCR in Telegram, ask about VAT, PIT, CIT, and ZUS, and get deadline reminders. Less clicking, fewer typos, more peace of mind.

Frequently Asked Questions (FAQ)

Where does the auto-filled company data come from? From the GUS registry (REGON database) — the name, registered address, and REGON number. VAT status and the account number are additionally pulled from the VAT white list, and for EU companies data is confirmed via VIES.

What exactly gets filled in from just the NIP? Usually the full company name, registered address, and REGON. Optionally, in the same step, also the VAT taxpayer status and account number from the white list.

Does this work for companies from the European Union? For foreign counterparties from the EU, verification and data go through the VIES system using a VAT number with a country prefix. That's a different source from the domestic REGON register, and the scope of data is often narrower.

Does auto-fill exempt me from checking the white list? No. Data from GUS tells you "who the company is," but you still need to keep an eye on VAT status and the account — ideally on the day of payment. Auto-fill makes this easier, because you do the verification along with entering the counterparty.

What if the data in the registry is out of date? Auto-fill reflects the state of the registry. If a company hasn't updated, say, its address in REGON, you'll get the older version — which is why it's worth confirming key fields with the counterparty.

Will the data land directly in my bookkeeping? In eKsięgowy AI, yes — the assistant is integrated with wFirma, so a completed counterparty is immediately ready for issuing an invoice or an e-invoice to KSeF.

This article is for informational purposes only and does not constitute tax advice. Consult an accountant or tax advisor in individual cases. Legal status: July 2026.