KSeF integration · Mandatory e-invoicing

Connect your ERP to KSeF before it becomes mandatory for everyone in 2027

We connect your ERP, CRM or accounting software to the official KSeF 2.0 API, so you issue and receive invoices from your usual workflow. For Polish and foreign companies invoicing in Poland.

Book your free KSeF assessment

30 minutes · free of charge · we'll be in touch to schedule

Key deadline Mandatory for all businesses from 1 January 2027
  1. 1 Feb 2026KSeF starts for large issuersMandatory issuing for businesses with 2024 sales above PLN 200 million, and receiving via KSeF, subject to legal exceptions.
  2. 1 Apr 2026KSeF for most companiesThe obligation to issue invoices in KSeF extends to most other taxpayers.
  3. 1 Jan 2027KSeF mandatory for everyoneThe exemption for small issuers ends. The law provides for penalties from this date, but the Ministry of Finance has announced a plan to defer them until the end of 2027.
Is your company ready for KSeF? Take the 2-minute check

From manual invoicing to invoicing from your own system

Today
With HolaPolska!
You enter every invoice twice: once in your ERP or CRM and again in the KSeF application.
The invoice leaves your system in FA(3) format and the KSeF number flows back into your records automatically.
You check by hand whether KSeF accepted or rejected each document and hunt for confirmations one by one.
Every invoice is linked to its final status, its KSeF number and its UPO.
A dropped connection or a KSeF outage stalls your invoicing or causes duplicate submissions.
Queues, retries and offline deadline tracking keep invoicing running, with no duplicates.

What you gain by integrating rather than working by hand

400 × 3 min = 20 h

See the time you lose today

That is what 400 invoices a month cost at 3 minutes of manual work each. In the assessment, we calculate your real figure.

Issue and receive

One flow for both

Receiving through KSeF has been mandatory since 1 February 2026. Your system downloads your suppliers' invoices incrementally.

Keep your ERP

Your tools adapt to KSeF

You keep your ERP, CRM or accounting software. A middleware connector absorbs API changes without disrupting day-to-day operations.

How an integrated invoice flows

  1. 01Your ERP or CRMThe invoice starts where you already work.
  2. 02Pre-validationData, amounts and the FA(3) schema checked before sending.
  3. 03KSeF 2.0 APISent in an interactive session or in batches.
  4. 04KSeF number + UPOFinal status and official confirmation of receipt.
  5. 05Accounting and paymentsEverything flows back, linked to your records.

Deliverables

What you get

Everything is set out in writing in the proposal: scope, deliverables, owners and acceptance criteria.

Book your free KSeF assessment

Proposal · KSeF integration

  • Systems and data assessment Which systems connect, what data you hold and which fields you still need for FA(3).
  • FA(3) data mapping Documented conversion to the official XML, including corrective, advance and final invoices.
  • KSeF 2.0 API connector Submission via interactive or batch sessions, plus incremental download of invoices received.
  • Status and UPO tracking Every invoice linked to its internal document, final status, KSeF number and official confirmation.
  • Contingency plan Queues, retries and deadline tracking for offline24, announced unavailability and failure mode.
  • Security and permissions Safe custody of certificates and tokens, least privilege, segregation of duties and an audit log.
  • Testing in TEST and DEMO Routine and edge-case scenarios validated before go-live, against agreed acceptance criteria.
  • Documentation and maintenance Manuals, test evidence and connector updates whenever technical or regulatory changes land.

How we work

How we take your integration into production

  1. 01

    Assessment and tax review

    We review your systems, data and volumes, and agree with your accountant which transactions go through KSeF.

  2. 02

    Solution design

    We choose between your ERP's native module, a connector or a bespoke build, and set the architecture, security and owners.

  3. 03

    Build or configuration

    We build the connector, the FA(3) mapping, pre-submission checks and status handling.

  4. 04

    Testing in TEST and DEMO

    We test corrective invoices, foreign currency, rejections, duplicates, outages and certificate expiry, without touching production.

  5. 05

    Go-live and maintenance

    We go live with monitoring and contingency in place, and keep the connector current as the API changes.

Who it is for

Your accountant stays in charge of tax

We handle the technical integration and the controls. VAT treatment, records and returns are set by your accountant or tax adviser, whom we work with from the assessment onwards.

  • High-volume businessesHundreds or thousands of invoices a month that no longer fit a manual process.
  • Recurring billingSubscriptions, licences, hosting or maintenance invoiced every period.
  • Foreign companies in PolandCompanies established here that invoice customers abroad in EUR or USD.
  • Accounting firmsAccess and documents for several client companies managed within KSeF.
  • SaaS and e-commerceKSeF invoicing built in for your own customers, with separate data and credentials.
  • Small issuers in transitionUp to PLN 10,000 gross a month in invoices: your deadline is 31 December 2026.

Frequently asked questions

Before you decide

Straight answers to the questions we are usually asked. If anything is still unclear, write to us.

It depends on your volume. With few invoices, the Ministry of Finance's free application may be enough. If you issue many invoices, bill on a recurring basis or work across several systems, integration removes double entry and gives you control of statuses, UPOs and contingencies. In the assessment, we tell you which option suits you.

As a guide: 1 to 4 weeks for a modern system with few flows; 4 to 12 weeks for an ERP or CRM covering issuing, receiving, permissions and corrections; 3 to 6 months or more with several systems, companies, currencies or high volumes. The real timeline depends on your access, the quality of your data and availability for testing.

We quote per project after the assessment. The drivers are data quality, how many systems we connect, volume, whether you need issuing, receiving or both, the range of tax scenarios and the support you require. You receive the scope, deliverables and acceptance criteria in writing.

Access to your system or its documentation, real sample invoices, a contact person on your team and your accountant's input to validate the tax treatment. KSeF authorisations are issued in your company's name and remain under your control.

It can. A company established in Poland may be required to issue invoices to customers abroad through KSeF, including in EUR or USD. We review this transaction by transaction with your accountant.

Want to dig deeper before deciding? Read the guide

Reach 2027 with your KSeF invoicing automated

In 30 minutes, we review your system, your volumes and the most sensible approach for your case. Free of charge, no commitment.

Book your free KSeF assessment