Luxembourg · Agentic SaaS development

SaaS Development for Luxembourg: Billing, VAT and Access

If your SaaS will bill the Luxembourg State, a municipality or a public establishment, every invoice has to be electronic, whatever the amount. A draft law, not yet passed, would extend that to business-to-business sales. Add VAT that depends on where each customer sits, accessibility rules in force since 28 June 2025 and buyers who may already sign in with LuxTrust, and billing and accounts carry more requirements than the interface.

Curiosive is a studio in Ankara, Türkiye, and its SaaS work is built by AI coding agents under senior engineer review. Engineers design the multi-tenant data model, tenant isolation, entitlements and billing webhooks; agents produce the CRUD screens, admin views, migrations and test suites around them. With the clock in Ankara one hour later in summer and two in winter, most office hours are shared.

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5+: years building for production
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VAT on SaaS sold from or to Luxembourg

Luxembourg's standard VAT rate is 17%. Goods and services listed in annexes C, A and B of the VAT law of 12 February 1979 are taxed at 14%, 8% and 3% respectively, so the rate a given service carries is something to confirm with an accountant rather than assume. Across borders, a business customer in another EU country usually pays VAT under the reverse charge, with important exceptions. Electronic services sold to consumers are taxed in the customer's country, though below a EUR 10,000 threshold they may be taxed where the seller is established, and the One Stop Shop lets a seller register in one EU country to declare that VAT. The product therefore records each customer's country and VAT status and the evidence behind every rate it applies. Agents write rate tables and tests; engineers own the logic choosing the rule.

E-invoicing for Luxembourg public-sector and B2B customers

The Law of 13 December 2021 made e-invoicing mandatory for every company that invoices the State, municipalities or public establishments, whatever the amount, and companies that do so only rarely can enter or upload compliant invoices through MyGuichet.lu. Draft Law No. 8815, filed on 30 July 2026, would extend the mandate to business-to-business transactions. It is a proposal, not yet law. As proposed, all Luxembourg companies would have to receive and process e-invoices from 1 January 2028, then issue them over the existing Peppol network from 1 July 2028 for large and medium-sized companies, or 1 January 2029 for all companies. At EU level, the VAT in the Digital Age directive provides for e-invoices to the European standard from 1 July 2030, though Member States may allow other standards domestically. Structured invoice data from day one makes Peppol output an integration, not a rewrite.

LuxTrust, a certification authority certified to issue PSD2- and eIDAS-compliant authentication certificates, sells strong customer authentication as a SaaS service that integrates over SAML2. The service runs from a Tier IV data centre in Luxembourg, and users sign in with the LuxTrust app, a SmartCard or the Scan device. For a B2B product whose customers already rely on LuxTrust, a login option is simpler when single sign-on is part of the identity layer from the start. Checkout has its own rule: under the PSD2 technical standards, payment providers may skip strong customer authentication for a remote electronic payment of no more than EUR 30, but only while the payer stays within a cumulative EUR 100 or five consecutive transactions since the last authentication. Checkout therefore has to expect some payments to trigger an authentication step, and subscription state follows the payment provider's events through idempotent webhooks.

The CNPD considers a cookie wall that forces users to click accept before reaching content as not producing valid consent. It recommends presenting accept and refuse identically and warns against a large accept button beside a small refuse link, or buttons that differ in font, colour, size or contrast. The marketing site and the signed-in product should both follow that. Luxembourg transposed the European Accessibility Act through the Law of 8 March 2023, in force since 28 June 2025 and enforced by OSAPS, which can fine an economic operator €250 to €15,000 for refusing requested documents or information, obstructing market surveillance or failing to comply with its decisions. The directive applies to listed services provided to consumers, such as e-commerce and consumer banking, and exempts service microenterprises, meaning fewer than 10 persons and an annual turnover or balance sheet total of no more than EUR 2 million.

Tenant isolation, data exports and EU Data Act switching duties

Engineers design tenant separation before agents generate anything on top of it. Two rules make per-tenant exports and clear supplier documentation worth building early. The EU Data Act, applying since 12 September 2025, requires switching terms in a written contract, with a notice period of no more than two months and a transitional period of no more than 30 calendar days, and from 12 January 2027 providers may not impose any switching charges. Separately, Circular CSSF 22/806 requires specialised and support PFS, POST Luxembourg and certain management companies to give at least three months' notice before outsourcing a critical or important function, ICT and cloud included, so such buyers may need lead time. We have built subscription products before, including Reveal Software (reveal.software), personal video onboarding for SaaS, and PicKey (pickey.ai), a visual password manager with subscription billing.

Proof

Published project examples

Reveal Software

Release Coach AI

Inspire Film

Poppin

Zing Coach

ChurchBee

AI-accelerated development

from$2,000

per month

Senior engineers building your product with AI coding agents: web, mobile, SaaS or browser extension, reviewed before anything ships.

Web, mobile, SaaS and browser extensions
AI-assisted delivery under senior engineer review
Scope and capacity agreed in writing, renews monthly

AI-accelerated development, billed monthly. We confirm scope, capacity and start date in writing before checkout.

Questions

The things people ask before starting.

Do we have to send e-invoices to public-sector customers in Luxembourg?

Yes, whatever the invoice amount, under the 2021 law. MyGuichet.lu covers companies that bill public bodies only rarely, but a SaaS that bills the public sector regularly is better off generating compliant e-invoices from its own billing system, with the invoice data stored in structured form.

Is B2B e-invoicing mandatory in Luxembourg yet?

Not yet. Draft Law No. 8815 would make it mandatory, but as of 5 October 2026 it is a proposal rather than law. As filed, companies would have to receive e-invoices from 1 January 2028 and issue them over Peppol from 1 July 2028 or 1 January 2029, depending on their size.

What VAT does a SaaS company in Luxembourg charge customers in other EU countries?

It depends on whether the customer is a business or a consumer. Businesses in another EU country usually account for the VAT themselves under the reverse charge. Consumer sales are taxed in the customer's country, subject to the EUR 10,000 threshold, and can be declared through one One Stop Shop registration.

How much does it cost to build a SaaS for the Luxembourg market?

Pricing for our one offer, AI-accelerated development, begins at $2,000 a month, billed in US dollars, and no long contract is required. Scope and monthly capacity are put in writing after a discovery call. A first slice reaches production early, then billing, VAT and e-invoicing follow as planned.

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What happens after you write to us.

01
You describe the product
One paragraph on what you are building, roughly when you need it, and who it is for. No brief, no form with fifteen fields.
02
You get a reply within a day
From the engineer who would do the work, not a sales team. If we are not the right fit we say so, and where possible we point you somewhere better.
03
You get a scoped plan
Scope, price and timeline in writing before anything is committed. You decide with the numbers in front of you.

No long contract to begin, no lock-in to our tooling, and the code is yours from the first commit.

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Looking for an engineering partner for the long haul?

A short note about the product, the timeline and who it is for is enough to start. You will hear back from the engineer who would do the work, not a sales team.

hello@curiosive.com See what we have shipped

Ankara / Türkiye · Working across European and US time zones

SaaS Development for Luxembourg: Billing, VAT and Access

VAT on SaaS sold from or to Luxembourg

E-invoicing for Luxembourg public-sector and B2B customers

Tenant isolation, data exports and EU Data Act switching duties