einvoice-preflight now has an Estonia page, the 23rd in its country set.
Most e-invoicing mandates are a date. Estonia's is a switch the buyer holds. Public buyers have taken e-invoices since 1 July 2019. Under Accounting Act amendments passed in September 2024 (Bill 428 SE), from 1 July 2025 any business registered as an e-invoice recipient in the Commercial Register can require its suppliers to send structured invoices. No registration, no obligation. So a supplier can be required to e-invoice by one customer and not by the next.
Guides name EN 16931 as the reference, with Peppol BIS Billing 3.0 in use and the older national XML standard still allowed by agreement. There is no central portal: invoices go through private service providers.
Sources disagree on 2027. Some describe a universal B2B mandate as planned; another calls 2027 a policy target with no statutory deadline. The page says so, rather than printing a date. Every fact comes from vendor guides and the European Commission's country sheet; the Accounting Act and the Tax and Customs Board site were not read (web fetch to those hosts failed from the build container), and the page says that too.