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Spain · Agentic SaaS development

SaaS Development for Spain: IVA, E-Invoicing and AI Agents

Spain's B2B e-invoicing clocks start with Orden HAC/1028/2026, published in the BOE on 5 October 2026 and in force from the following day. Under Real Decreto 238/2026, businesses whose turnover exceeded 8 million euros in the previous year have 12 months from that point and everyone else has 24. A subscription product that bills Spanish companies needs invoices structured to the EN 16931 model, plus tax logic that knows where each customer sits.

Curiosive is a studio in Ankara, Türkiye, that builds subscription products with AI coding agents under senior engineer review. Engineers design the tenant model, billing webhooks and entitlement logic that decide who sees what and who pays what. With Ankara one or two hours ahead of mainland Spain depending on the season, we share most of your working day.

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IVA on SaaS subscriptions sold to customers in Spain

Spain's standard IVA rate is 21%. Electronically supplied services to non-business customers established or resident in the Spanish VAT territory are taxed there when the seller is established outside the EU, and when it is established only in another Member State once it passes the Article 73 threshold or opts for taxation at destination. Under the wider EU rules, services sold to businesses in another EU country usually fall under the reverse charge, with several important exceptions, and a seller can register in one EU country through the One Stop Shop to declare and pay VAT on cross-border supplies of services to EU customers. One detail catches billing code: the Canary Islands, Ceuta and Melilla sit outside the Spanish VAT territory, so a Spanish address alone does not settle the tax. Billing needs the customer type and region stored with each invoice. An accountant should confirm the treatment for your plans.

B2B e-invoicing in Spain: Real Decreto 238/2026 and Facturae

Real Decreto 238/2026, de 25 de marzo, in force since 20 April 2026, implements the mandatory B2B e-invoicing of Ley 18/2022. Invoices follow the EN 16931 model in CII, UBL, EDIFACT or Facturae syntax, and the 12 and 24 month periods count from the entry into force of the Ministry of Finance order on the public e-invoicing solution. If your product issues or records invoices for Spanish businesses, Article 201 bis of the Ley General Tributaria matters as well: producing or marketing billing software that allows separate accounts, unrecorded, false or altered transactions, or that fails the integrity, traceability and inalterability specifications, is a serious infraction fined a fixed 150,000 euros per financial year with sales and per type of system. That is why invoice numbering and records are designed by engineers, so that no agent-written change can quietly alter them.

Founding a SaaS company in Spain: startup tax and Madrid funding

Founders building a subscription product from Spain can plan around Ley 28/2022, de 21 de diciembre. Companies certified by ENISA as an 'empresa emergente' pay corporate tax at 15% in their first year with a positive tax base and the following three years. Certification generally requires no more than five years since registration (seven in biotech, energy, industrial and other strategic sectors), a seat in Spain and 60% of staff on Spanish employment contracts. The funding picture has figures too. Startup Genome's Madrid profile in the Global Startup Ecosystem Report 2026 ranks Madrid ninth among European startup ecosystems and values it at $22 billion (H2 2023 to 2025), with $852 million in Seed and Series A funding over H2 2023 to 2025.

Data Act switching and accessibility rules for SaaS sold in Spain

The EU Data Act has applied since 12 September 2025, and its recitals place SaaS among data processing services. Switching terms must sit 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. A clean export per customer is far easier when tenant separation is in the data model from the first migration. Accessibility is the other early decision. Spain transposed the European Accessibility Act in Title I of Ley 11/2023, de 8 de mayo, whose requirements apply from 28 June 2025 to consumer services including e-commerce, consumer banking, e-books, electronic communications and social networks, with surveillance authorities designated by each autonomous community and by Ceuta and Melilla. The Directive itself exempts microenterprises providing services: fewer than 10 persons and no more than EUR 2 million of annual turnover or balance sheet total.

What AI agents write in a SaaS product and what engineers design

Coding agents take scoped tasks for the large, predictable parts: CRUD screens, admin views, migrations, Playwright end-to-end tests and unit tests. A senior engineer reviews every diff. Engineers design the parts where a mistake leaks data or money: the tenant model, plan and entitlement rules, IVA calculation, invoice records and billing webhooks, which are idempotent so a redelivered event changes nothing. Checkout and card-update flows expect a strong customer authentication step, because under the PSD2 standards the exemption for remote payments of no more than EUR 30 holds only while payments since the last authentication stay within a cumulative EUR 100 or five consecutive transactions. For a client in Spain we built Inspire Film (inspire.film), a virtual cinema with streaming, live events and per-title entitlement. PicKey (pickey.ai), with its subscription billing, follows the same split.

Proof

Published project examples

Reveal Software

Reveal Software

Release Coach AI

Release Coach AI

Inspire Film

Inspire Film

Poppin

Poppin

Zing Coach

Zing Coach

ChurchBee

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.

What VAT rate applies to SaaS sold to consumers in Spain?

The standard IVA rate of 21% applies where the service is taxed in the Spanish VAT territory. That territory excludes the Canary Islands, Ceuta and Melilla, so billing logic should not apply 21% to every Spanish address. Sellers can use the One Stop Shop to declare cross-border consumer sales from one EU country.

When does B2B e-invoicing become mandatory in Spain?

Twelve months after Orden HAC/1028/2026 enters into force for businesses whose turnover exceeded 8 million euros in the previous year, and 24 months after it for all others. The order was published in the BOE on 5 October 2026 and enters into force the following day, which starts both clocks.

Does strong customer authentication apply to cheap SaaS subscriptions in Spain?

It can. The EUR 30 low-value exemption in the PSD2 standards lasts only while a payer's remote payments since the last authentication stay within EUR 100 in total or five consecutive transactions, so a low price alone does not remove the authentication step from checkout.

How much does it cost to build a SaaS product for Spanish customers?

Pricing starts from $2,000 per month for AI-accelerated development, in US dollars, with scope and capacity set in writing after a discovery call. Structured EN 16931 invoices, IVA rules by region and an SCA-ready checkout are worth raising in that call, since each adds engineering work.

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How it starts

What happens after you write to us.

  1. 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.

  2. 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.

  3. 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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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.

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Ankara / Türkiye · Working across European and US time zones