Preparing for mandatory e-invoicing takes ten steps: map your invoicing flows, check your software, clean up master data, choose an operating model, choose a provider, bring your accountant in, plan out 2026, assign ownership of the process, test the failure scenarios and run a final readiness audit.
2026 is not a postponement, it is a preparation period. Companies that miss it will spend December 2026 choosing a provider, adapting software, cleaning master data and training people all at once. This article is a condensed preparation plan; each topic is covered in depth in the articles it links to.
The ten steps
1. Map where the obligation touches you. Take an inventory of your invoicing flows: outgoing and incoming domestic B2B invoices, invoices to public bodies, cross-border invoices, corrections and credit notes, advance payments and settlements, self-billing, internal approval. Until 2030 the obligation covers domestic documents only — see Who is affected and from when.
2. Check your existing software. Ask your accounting or ERP vendor specific questions: can the system create a structured invoice, can it also receive and process one, can it connect to the Peppol network, can it handle corrective documents, can it show processing status and errors.
3. Audit your master data. Check company registration numbers, tax and VAT identifiers, legal name, address, bank accounts, internal partner codes and document number ranges. Electronic invoicing will not fix data errors, but it will expose them — in Peppol, correct identification of the recipient is technically critical.
4. Choose your target operating model. Manual (application plus accountant), hybrid (export from the accounting system and upload) or integrated (direct ERP connection). Not every company needs the same thing.
5. Choose a delivery service provider. Do not look at price alone: a web interface for smaller companies, an API for integration, support for an external accountant, SLA and monitoring, handling of error states, archiving of originals. How the choice is made and what happens when you move is described in Choosing and changing your provider.
6. Bring your accountant into the topic. An external accountant needs to know where invoices will come from, who checks them, what is automatic and what is manual, and who handles errors. They can be invited into your mailbox as another user.
7. Do not wait for the last quarter of 2026. A sensible split of the year: second quarter for choosing a solution and a readiness audit, second to third for technical changes and testing, third to fourth for a pilot run and internal training, fourth for live readiness and a fallback plan.
8. Assign ownership of the process. “IT takes care of it” is not enough. A company needs to know who owns the process, who talks to the software vendor and to the provider, who handles incidents, and who verifies that invoices arrived, left and were processed correctly. This ties into deadlines and penalties — see Deadlines, data reporting and penalties.
9. Test the failure scenarios. Do not plan for the happy path only. Try incomplete invoice data, an unidentifiable recipient, a duplicate, a credit note, a corrective invoice, an integration outage, and the case where the recipient is not ready for automated processing.
10. Run a final readiness audit. Just before going live, the company should be able to answer yes to the questions below.
Final audit: can we do it?
| Question | |
|---|---|
| Can we issue an invoice and can we receive one? | |
| Can we identify a partner in the network? | |
| Can we get an invoice into our accounting system? | |
| Can we handle errors, and can the accountant work with them? | |
| Do we have a provider chosen both contractually and technically? | |
| Can we keep the original XML file and prove delivery? | |
| Can we process a credit note and a correction? | |
| Do we have a fallback plan for an outage? |
If the answer to any question is no, readiness is not complete yet.
By company size
Sole trader or small company. With a few dozen invoices a month the priority is not integration but simplicity: reliable access to the delivery service, a clear interface and the option to give your accountant access.
Mid-sized company. With internal administration, several users or invoice approval, a hybrid or integrated model pays off. The goal is to reduce manual work and avoid entering the same data twice.
Larger company with an ERP. E-invoicing is a transformation project: master data changes, field mapping, test scenarios, workflow, exceptions, an audit trail and provider SLAs. Integration can take days to weeks.
Where ePostman helps
Steps 5 to 9 are exactly what a delivery service covers: sending and receiving over Peppol, five-level document validation, reporting invoice data to the Slovak tax authority, an archive of originals with proof of delivery, and an interface for your accountant. Steps 1 to 4 are on your side and no provider can do them for you.
How to set up an account is described in Setting up your account.
Frequently asked questions
When should a company start preparing for e-invoicing?
During 2026. A sensible split is choosing a solution and a readiness audit in the second quarter, technical changes and testing in the second to third, a pilot run and training in the third to fourth, and live readiness with a fallback plan in the fourth.
What do companies underestimate most when preparing?
The quality of master data, and time. Partner identifiers — company registration, tax and VAT numbers — must be in order, because correct identification of the recipient is technically critical in Peppol. Integrating an older or custom system can take days to weeks.
Is an application without ERP integration enough?
With a few dozen invoices a month it usually is: you need reliable access to the delivery service, a clear interface and the option to give your accountant access. With higher volumes, approval flows or several users, a hybrid or integrated model pays off.