KSeF from 1 February 2026 — the last 30 days of rollout
- #KSeF
- #e-invoicing
- #rollout
What MUST work on 1 February
- Issuing gateway for FA(2)-format invoices.
- Token / certificate authenticating the company in KSeF (issued by the local tax office head).
- Permission policy — who issues, who approves, who reads.
- Fallback procedure — what you do when KSeF goes down (and it will).
What can wait until Q1
- Credit notes (their handling in KSeF is complicated).
- ERP integration (if you issue via an external gateway).
- Sales team training (account managers often don't realise the customer no longer gets a PDF).
Common last-minute mistakes
1. Tax officers not registered. The company is registered in KSeF, but individual users aren't. Invoices don't go out.
2. Wrong counterparty NIPs in the database. KSeF rejects invoices when the NIP doesn't match the VAT status. The database needs cleaning before go-live.
3. Wrong currency conversions. KSeF requires PLN. Invoices in EUR/USD must use the previous business day's NBP rate — automation sometimes picks the wrong one.
4. Missing recipient acceptance. FA(2) has a recipient acceptance field — some industries don't know it exists.
What KSeF won't do
- It won't replace your internal approval workflow.
- It won't issue pro-forma invoices (those stay outside the system).
- It won't post invoices to the books — you need integration with your accounting system.
Plan for the last 30 days
Week 1: test issuing a full series of invoices (different types, different counterparties). Week 2: train sales and the people who actually issue invoices. Week 3: notify customers (most often forgotten). Week 4: buffer for unexpected issues.
We run KSeF rollouts end-to-end, from audit to the first live invoice. If you feel you won't make it — let us know. Our team has shipped 30+ clients through it already.