Two dates, two different obligations.
Receiving is already settled: since January 1, 2025 every German business must be able to accept a structured e-invoice, and the Ministry of Finance states plainly that no exemptions exist and that a plain e-mail inbox is enough. Issuing is staggered: from 2027 for businesses whose prior-year turnover exceeded 800,000 euros, from 2028 regardless of turnover, with small-scale traders under the §19 regime permanently allowed to send ordinary invoices. Private customers never trigger the e-invoice duty, though work on a building still has to be invoiced within six months.
Progress billing, site measurements, reverse charge.
A trade business does not send one invoice per job. It sends progress invoices, then a final or residual invoice, it bills construction work under the reverse-charge rule of §13b, and it attaches measurement sheets and a bill of quantities. Each of those has its own answer in the German rules: interim invoices issued before your own start date stay exempt, the deduction of interim payments may sit in an attached unstructured file, the detailed bill of quantities may be an attachment as long as the structured part names it, and the 250-euro small-amount exemption explicitly does not apply to reverse-charge construction work.
From the site to the ledger, without retyping.
Craft software mostly covers the outgoing side, and vendors document their own limits: one supports ZUGFeRD output but states that XRechnung import is still to come, another sells e-invoicing and accounting as separate modules. We build the route between the systems you already run, incoming supplier invoices checked and handed to the bookkeeping, outgoing invoices produced in the right format per customer, validated, dispatched and archived, and we then operate it for you.