From 1 January 2027 penalties for invoices outside KSeF
Shopify invoices reach KSeF on their own
The buyer enters a NIP in the cart and, once the order is paid, the FA(3) invoice reaches KSeF by itself. The KSeF number and a PDF with a QR code are saved on the order. You retype nothing.
- Free plan: 5 invoices a month
- Works on every Shopify plan
- Admin in Polish, English and Ukrainian
The app arrives in the Shopify App Store in December. Join the list and we will let you know on launch day and help with setup.
- Official KSeF 2.0 API
- Ministry of Finance FA(3) schema
- Rates from api.nbp.pl
- Servers in the EU
KSeF Faktury is a Shopify app that issues an FA(3) invoice for every paid order with a Polish NIP and sends it to KSeF, Poland's National e-Invoicing System. Launching in the Shopify App Store in December 2026.
When KSeF becomes mandatory: 2026 and 2027
- 1 February 2026Issuing in KSeF mandatory for firms with 2024 sales above PLN 200 million incl. VAT. From this day every firm receives invoices through KSeF.
- 1 April 2026Mandatory for all other taxpayers. Until 31 December 2026 invoices may be issued outside KSeF while those covered by the obligation stay under PLN 10,000 gross a month (consumer invoices and receipts do not count).
- 1 January 2027The PLN 10,000 exemption ends and penalties start (art. 106ni of the VAT Act): up to 100% of the VAT on an invoice issued outside KSeF, or 18.7% of the gross amount when the invoice shows no VAT.
KSeF (Krajowy System e-Faktur) is the Polish Ministry of Finance system that structured invoices pass through. As a rule, an invoice to a business issued outside KSeF is not validly issued; the exceptions are the offline modes, the PLN 10,000 limit and receipts with a NIP up to PLN 450 until the end of 2026. From 2027 an invoice to a business for a cash-register sale also goes through KSeF.
Legal status as of 18 October 2026. Sources: KSeF rollout stages · PLN 10,000 limit · KSeF 2.0 questions and answers · Act of 5 August 2025 (Dz.U. 2025 item 1203)
How it works
One permission granted once, then everything runs by itself.
- 1
Install the app
Enter your NIP, company name, address and number pattern, e.g. FV/2026/12/1. Numbering is continuous, with no gaps.
- 2
Connect to KSeF
In the KSeF Taxpayer App you give our certificate the right to issue invoices. The wizard guides you and checks the connection itself.
- 3
Turn on the NIP field in the cart
One click in the theme editor. No code changes.
- 4
Sell
Every paid order with a NIP gets an invoice in KSeF. A refund gets a correction.
This is the invoice your customer gets
A PDF in the Ministry of Finance visualisation layout: the KSeF number in the header and a QR code anyone can use to check the invoice in KSeF. The buyer downloads it from the order page; you have it on the order in Shopify.
5260250274-20261218-9A1C2E4F7B30-61| No. | Item | Qty | Gross price | Rate | Gross value |
|---|---|---|---|---|---|
| 1 | Ceramic mug 350 ml | 4 | 49.00 | 23% | 196.00 |
| 2 | Shipping: DPD courier | 1 | 15.99 | 23% | 15.99 |
- Net
- PLN 172.35
- VAT 23%
- PLN 39.64
- Total due
- PLN 211.99
Paid by card, 18.12.2026
- 1
KSeF number
Assigned by the Ministry of Finance when the invoice is accepted. From that moment the invoice legally exists.
- 2
QR code
Leads to the invoice check in KSeF. A buyer without KSeF access can still confirm the invoice is genuine.
- 3
Currency and NBP rate
An order in euro gets an invoice in euro, with VAT converted to złoty, the table number and the rate date.
Everything a store selling to businesses needs
NIP in the cart
The "I need a company invoice" field checks the NIP checksum on the spot. A wrong number stops checkout.
Invoice after payment
Once the order is paid, an FA(3) invoice goes to KSeF. The KSeF number and the official receipt (UPO) come back.
Corrections on refunds
A refund in Shopify creates a correction invoice linked to the original KSeF number, with its own FVK series.
Ministry of Finance PDF
PDF in the Ministry of Finance layout with a QR code. The buyer downloads it from their order page.
Problems screen
Wrong NIP, rejected invoice or a KSeF outage: you see what happened and what to click. Unsent invoices wait in the queue.
Export for your accountant
Every month a CSV with net, VAT and gross amounts, or a ZIP with the XML and PDF of every invoice.
By hand or automatic
How long one business invoice takes when the store issues it by hand in invoicing software, and with the app.
| Step | By hand | KSeF Faktury |
|---|---|---|
| Copy order data and the NIP | 3-5 min | 0 min |
| Check the NIP and the buyer's VAT status | 1-2 min | 0 min, in the cart |
| Send to KSeF and read the KSeF number | 1-3 min | 0 min |
| PDF for the customer and the invoice email | 1-2 min | 0 min |
| NBP rate for an order in euro | 2-4 min | 0 min |
| Correction on a refund | 5-10 min | 0 min |
| At 100 invoices a month | 10-20 hours | a few minutes to review the list |
Our assumption: 100 invoices a month at 6-12 minutes of manual work per invoice, correction and rate. An estimate for a typical store that issues invoices separately in invoicing software.
Is your store ready for KSeF?
Five questions, one minute. At the end, a list of what is missing.
Secure by design
No passwords or tokens
You never give us your KSeF login or a token. You grant a permission to the app's certificate in the official Taxpayer App.
Revoke in one click
Withdraw the permission in KSeF at any time. From that second the app cannot send anything on your behalf.
Data stays in the EU
Servers and backups in the EU. We process only the data an invoice needs, under GDPR.
For accounting offices
Do your clients run Shopify stores? Each of them gets a list of invoices with KSeF numbers and a monthly export in one click. Write to us: we will help connect your clients and agree terms for your office.
Pricing
Billed by Shopify on your store bill. Every plan has every feature.
-
Free
$0 / month
5 invoices a month
-
Most popular
Start
$12 / month
100 invoices a month
-
Pro
$24 / month
500 invoices a month
-
Unlimited
$49 / month
Unlimited invoices
Prices in USD. We count invoices and corrections accepted by KSeF in a calendar month. Over the limit, new invoices wait in the queue and go out automatically after an upgrade: nothing is lost.
Questions and answers
Do I have to give the app my KSeF password or a token?
No. In the KSeF Taxpayer App you grant a permission to the app's certificate (by its fingerprint). Passwords and tokens stay with you, and you can revoke the permission at any time.
Which orders get an invoice?
Paid orders where the buyer entered a valid Polish NIP. Orders without a NIP are skipped: you keep issuing fiscal receipts as before.
Do you support orders in euro?
Yes. The invoice is in the currency the buyer paid in, and VAT is also shown in PLN at the NBP average rate (table A) of the last business day before the tax point (art. 31a(1) of the Polish VAT Act); in a store paid up front that is usually the payment date. We take the rate automatically from the official service of Narodowy Bank Polski (api.nbp.pl), and the table number and rate date are printed on the invoice.
What happens on a refund?
The app issues a correction invoice that references the original KSeF number and sends it to KSeF. Partial and full refunds work, shipping included.
What if KSeF is down? (offline mode)
Invoices wait in the queue and go out automatically when KSeF is back. The Problems screen shows what is waiting and why. During an announced KSeF outage the law provides offline modes, including offline24: the invoice must reach KSeF by the next business day.
Token or KSeF certificate? Will tokens expire?
The app uses a certificate: you grant it a permission in the Taxpayer App and copy nothing. The Ministry of Finance announced that KSeF tokens stay valid indefinitely (KSeF 2.0 Q&A, question 39), so articles saying they end in 2026 are out of date.
Does an invoice to a private person have to go to KSeF?
No. A consumer invoice may go to KSeF voluntarily, but it does not have to. The app issues KSeF invoices for orders with a NIP, that is for businesses.
Does it work on my Shopify plan and theme?
Yes. The NIP field is a theme block you turn on in the editor without code. Shopify Plus is not required.
Can I use my own invoice numbering?
Yes. Set a pattern such as FV/{YYYY}/{MM}/{N}. Numbers are continuous within each month; corrections have their own FVK series.
The buyer entered a wrong NIP. What now?
The order appears on the Problems screen. Enter the correct NIP and the app issues the invoice and sends it to KSeF.
Who is behind the app?
The app is built by the software house Lytvynov Production, founded by Anton Lytvynov. We test it on the Ministry of Finance KSeF 2.0 test environment. We answer in Polish, English and Ukrainian: kontakt@ksefshop.pl.
Be ready before 1 January 2027
Setup takes about 10 minutes. The free plan is enough to check everything on a live store.
Join the start list