Quick verdict: From 1 January 2027, companies with more than EUR 800,000 in prior-year turnover must issue e-invoices; from 2028, everyone. If you have to touch your legacy system anyway, consider switching to Odoo: XRechnung, ZUGFeRD and Peppol are standard, the DATEV export stays, and master data, open items and number ranges move over in a fixed-price project.
Why the switch is due now
An e-invoice is an invoice issued, transmitted and received in a structured electronic format that allows electronic processing (Section 14(1) sentence 3 UStG). The format must comply with EN 16931 or be agreed bilaterally, provided a correct and complete extraction is possible (Section 14(1) sentence 6 UStG). A PDF without embedded data is not an e-invoice but an "other invoice" (BMF circular of 15 Oct 2024, para. 7).
The deadlines from Section 27(38) UStG:
| Date | Rule |
|---|---|
| 1 Jan 2025 | Reception duty for all businesses established in Germany; an e-mail inbox is sufficient (BMF circular of 15 Oct 2024, para. 40) |
| until 31 Dec 2026 | Transition: paper or – with the recipient's consent – another electronic format remain permitted (no. 1) |
| 1 Jan 2027 | Issuing obligation where total turnover in the previous calendar year exceeded EUR 800,000 |
| until 31 Dec 2027 | Transition for companies up to EUR 800,000 prior-year turnover (no. 2) and for EDI procedures (no. 3) |
| 1 Jan 2028 | Issuing obligation for all |
The sanction that bites in daily business is not the fine of up to EUR 5,000 under Section 26a(2) no. 1 UStG. It is your customer: an "other invoice" that should have been an e-invoice does not, in principle, entitle the recipient to deduct input VAT (BMF circular of 15 Oct 2024, para. 56). Purchasing departments will reject such invoices to limit their own risk.
For four widespread systems the e-invoicing mandate coincides with a second date:
| System | Vendor date | What it means |
|---|---|---|
| Microsoft Dynamics NAV 2017 / 2018 | Extended support ends 12 January 2027 and 12 January 2028 respectively | The official path is Business Central; any investment in NAV is an investment in a system without vendor support. |
| Sage 100 Desktop | without updates since 1 January 2025 | New format versions no longer reach the desktop installation through the vendor. |
| SAP Business ByDesign | no longer available to new customers since 20 April 2026 | Existing customers receive maintenance but no strategic development; SAP recommends S/4HANA Cloud. |
| Lexware | no vendor date | The question is not support but whether the company has outgrown an architecture built for very small businesses. |
If a system replacement is already planned within the next year or two, include it in your e-invoicing plans. This helps you assess which legacy changes still make sense and whether bringing the migration forward is practical.
What Odoo provides for e-invoicing
Odoo provides e-invoicing through its general EDI module. The German localisation documentation for versions 19.0 and 20.0 has no dedicated section, and Germany is absent from the e-invoicing country list. The following functions were checked against the available documentation and source code:
| Requirement | In Odoo | Basis |
|---|---|---|
| XRechnung (UBL) | Community module account_edi_ubl_cii with an XRechnung builder in versions 17 to 20; the XRechnung 3.0 identifier is verified for 18, 19 and 20 | odoo/odoo source code |
| ZUGFeRD / Factur-X | Every invoice PDF generated by Odoo contains a Factur-X XML; Odoo produces the EXTENDED profile, there is no profile selector | source code, Odoo documentation 17.0 |
| Format per customer | The invoice format is set on the customer's Accounting tab | Odoo documentation 17.0 |
| Peppol | Odoo acts as access point and SMP; registration is free, also in the Community edition; sending formats BIS Billing 3.0, XRechnung CIUS, NLCIUS | Odoo documentation 19.0 |
| Reception | An e-mail alias turns PDF and XML into draft bills; XML files need no OCR credits; Peppol inbound several times a day as drafts in the purchase journal | Odoo documentation 19.0 |
| DATEV | l10n_de (Community) with GoBD audit trail; l10n_de_reports (Enterprise) with the exports "DATEV DATA (ZIP)" and "DATEV ATCH (ZIP)" | Odoo documentation 19.0 |
| Leitweg-ID (B2G) | Odoo 20 takes the Leitweg-ID from the contact into field BT-10; in versions 17 to 19 the field reads "N/A" when empty | odoo/odoo source code |
Record the limitations in the specification too: Odoo has no KoSIT validation report and generates Factur-X only in the EXTENDED profile. A user report for Odoo Online 19.2 notes that Factur-X is missing for self-billing vendor credit notes. XRechnung or ZUGFeRD? A decision guide explains format selection; Registering Peppol in Odoo covers the network connection.
From Lexware to Odoo
What changes for your invoices. Lexware Office, Plus and Premium are designed for very small businesses with classic bookkeeping and manageable order processing. Many Lexware users are below EUR 800,000 in turnover and fall under the issuing obligation only in 2028 – but they have had to receive since 2025. Whether and to what extent your Lexware version issues, receives and archives e-invoices is a question for the vendor.
What Odoo does instead. The invoice format is set per customer: XRechnung for business customers and public authorities, the Factur-X PDF for everyone else. Inbound invoices arrive as drafts via e-mail alias or Peppol. On top you get what Lexware does not cover: multi-location inventory, manufacturing, CRM, web shop and multi-company capability.
The migration path. Lexware’s data exports provide the basis for the following steps:
- Master data – customers, suppliers, products, accounts, prices – via CSV export; for each customer we add the e-invoice format and the invoicing e-mail address.
- Open items and stock as the opening balance on the cut-over date; older documents stay in the legacy system.
- Number ranges: whether the existing range continues or a new, clearly separated range starts on the cut-over date is agreed with your tax adviser.
- DATEV continuity: your tax adviser keeps receiving journal entries and documents in DATEV format, from Odoo Enterprise via
l10n_de_reports. - Payroll: companies that run payroll in-house with Lexware Lohnautopilot keep that module in parallel; every other area moves.
Typical project duration: 8 to 14 weeks. The full comparison is in Odoo vs Lexware.
From Sage 100 to Odoo
What changes for your invoices. Sage 100 is typically run on-premises with a Microsoft SQL Server; according to the vendor, the desktop edition has been without updates since 1 January 2025. For e-invoicing this means format maintenance, new XRechnung versions and validation rules no longer reach the installation through the regular update path. Which e-invoicing functions your Sage 100 installation and its extensions offer today is a question for your Sage partner.
What Odoo does instead. XRechnung and Factur-X come from the Community module that is maintained with every Odoo version; Peppol is connected without a third-party provider. Accounting stays on SKR03 or SKR04, the DATEV export stays.
The migration path. Sage 100 has an accessible SQL database, which eases extraction:
- Master and transaction data – customers, suppliers, products, prices, accounts, documents, balances – via SQL from the Sage database.
- Mapping into the Odoo data model: accounts can usually be taken over 1:1, master data almost; per customer we add format and Peppol identifier.
- Open items on the cut-over date; documents older than three years as historical data.
- Number ranges and journals per legal entity; with several companies, separate ranges so that DATEV does not reject duplicate numbers.
- DATEV: your tax adviser receives the same file formats as before from Sage.
Typical project duration: 12 to 20 weeks. The comparison of both systems is in Odoo vs Sage 100.
From Dynamics NAV / Navision to Odoo
What changes for your invoices. For Dynamics NAV 2017 and 2018, extended support ends according to Microsoft on 12 January 2027 and 12 January 2028 respectively – the second date coincides almost to the day with the issuing obligation for all companies. Microsoft's path is Business Central; the DATEV connection there runs through paid extensions such as Continia or specialised partners. Which e-invoicing functions your NAV installation and its add-ons offer today is a question for your partner.
What Odoo provides. XRechnung, Factur-X and Peppol are standard functions. Odoo Enterprise includes DATEV export without an additional licence. Groups can manage multiple entities and consolidation within one database.
The migration path. Existing C/AL or AL customisations in NAV affect the workload and are assessed separately:
- Extraction of master and transaction data from the SQL back end or via the web API.
- Inventory of customisations: every extension is documented, assessed and classified as standard, configuration or development in Odoo.
- Open items and stock on the cut-over date; number ranges per legal entity.
- DATEV continuity via
l10n_de_reports; test export with your tax adviser before go-live. - Test run in a sandbox with plausibility check of the balances.
Typical project duration: 16 to 28 weeks. Comparison and decision guide: Odoo vs Dynamics 365 Business Central and Odoo vs Dynamics 365.
From SAP Business One to Odoo
What changes for your invoices. SAP Business One is sold exclusively through certified partners and extended with add-ons; the current version 10 runs on Microsoft SQL Server or SAP HANA. For the sister product Business ByDesign, the vendor stopped sales to new customers on 20 April 2026 – companies running it find the path in SAP Business ByDesign to Odoo. Which e-invoicing functions your B1 installation and its add-ons cover is a question for your SAP partner.
What Odoo provides. E-invoicing is included as standard. Enterprise includes DATEV export, and Peppol needs no additional provider. The webshop, CRM and marketing share the same data model.
The migration path. B1 has an openly documented database structure:
- Extraction of master and transaction data directly from the SQL Server or via the DI API.
- Mapping with adjustment of charts of accounts and tax codes; format and identifier per customer.
- Assessment of add-ons: what ran through extensions in B1 is often standard in Odoo; industry-specific parts are rebuilt or covered from the Apps Store.
- Open items on the cut-over date; number ranges; DATEV test export.
- Complete test migration into a sandbox, plausibility check of the balances.
Typical project duration: 14 to 24 weeks. Comparison: Odoo vs SAP Business One and our blog post Odoo vs SAP Business One for the Mittelstand.
What stays the same in every switch
Regardless of the legacy system, five points are settled in every e-invoicing switch:
- Customer master data. For every customer we define which format they receive, whether they are reachable via Peppol and – for public authorities – which Leitweg-ID belongs in field BT-10. The migration is the right moment to clean up VAT IDs and invoicing e-mail addresses.
- Recurring invoices and contracts. Contracts can be regarded as invoices; for a continuing obligation one e-invoice for the first partial-performance period with the contract attached is sufficient. For recurring invoices issued as "other invoices" before 1 January 2027 there is no duty to issue an additional e-invoice as long as the invoice details do not change (BMF circular of 15 Oct 2024, paras. 44–46). Review your recurring invoices before the cut-over date.
- Corrections. An "other invoice" that should have been an e-invoice can be corrected retroactively by an e-invoice with a specific and unambiguous reference (para. 57). Cash discounts require no correction; changes to the scope of supply do, optionally as a credit note referencing the original invoice (BMF circular of 15 Oct 2025, paras. 51a, 51b). Corrections to legacy invoices are issued from Odoo after the cut-over date.
- Retention. E-invoices must be kept for eight years, at least their structured part in a way that it remains intact in its original form (para. 60). The legacy system stays readable for the statutory retention period; whether an archive export is sufficient is agreed with your tax adviser.
- DATEV. Your tax adviser receives data from Odoo in the existing DATEV format. A test export verifies the handover before go-live.
The fixed-price process
| Phase | Content | Result for you |
|---|---|---|
| 1. Pre-analysis | Legacy system, document volume, customer structure (B2B, B2G, abroad), interfaces, customisations | Scope and price. For projects with a clearly bounded scope you receive the binding fixed-price quote within five working days of the first meeting; for company groups it follows the pre-analysis. |
| 2. Specification | Every requirement as standard, configuration or development; formats per customer group; journals, number ranges, DATEV hand-over | One document that acceptance is measured against. Already have a requirements document? Send it to us. |
| 3. Migration | Master data, open items, stock; test migration into a sandbox | Completeness and balances checked before anyone works productively |
| 4. Test run with validation report | Test invoices per format and channel; check with the KoSIT validator; test reception via e-mail and Peppol; DATEV test export to your tax adviser | One validation report per format, which you keep (BMF circular of 15 Oct 2025, para. 35a) |
| 5. Go-live | Cut-over at a quarter or financial-year end; standby during cut-over | One clean cut, no double maintenance |
| 6. Aftercare | 60 days with short response times and weekly reviews | Then transition into regular support |
The specification defines the scope covered by the binding price. We bear any additional effort within that scope. Licence fees published at odoo.com/pricing are listed separately over five years. Our packages are on the pricing page.
Next step
We use e-invoices for our own billing and have supported clients in Germany and abroad through their Odoo implementation.
- You want to know whether your legacy system will meet the deadline: complete the readiness check – twelve questions, result shown on the page right away.
- You want to plan the switch in concrete terms: request an e-invoicing consultation. The scope of the service is described on E-invoicing with Odoo.
- You want to see Odoo first: create an Odoo test database.
The full overview of deadlines, formats and Odoo versions is in the guide E-invoicing with Odoo and on the topic page E-invoicing.