Luxembourg's draft law No. 8815 would make structured B2B e-invoicing mandatory between domestic businesses: receiving from 1 January 2028, issuing for large and medium businesses from 1 July 2028 and for the rest from 1 January 2029, over Peppol in an EN 16931 format.
What a search today found: the Finance Minister deposited the bill on 30 July 2026; the Chamber's Finance Committee heard it on 18 September and appointed a rapporteur; the dates did not change; as of 30 September a tracker still showed it as deposited, with no Council of State opinion filed. Nothing later turned up. These are secondary reports (the Chamber's site was unreachable from our network), so treat the dates as a draft's.
The Luxembourg page in E-invoice Preflight carries this status. The free checker tests an EN 16931 UBL or CII file against the Peppol BIS rules in your browser, so you can test sample invoices before an access point sees them. Not legal or tax advice.