This case study examines the BATUZ digital system of Biscay, Spain. BATUZ is an integrated digital tax administration system comprising certified e-invoicing (TicketBAI), a real-time ledger of economic operations (LROE), and automatic preparation of draft tax returns. The analysis maps BATUZ throughout the lens the six dimensions of the OECD Digital Government Policy Framework, presenting how a subnational government with fiscal autonomy can leverage digital technologies to underpin tax reforms.
Leveraging digital technologies and data into Biscay’s tax administration
Abstract
Tax administrations across OECD countries are looking to increase tax collection in less burdensome ways, including by leveraging digital technologies and data. The Provincial Council of Biscay in Spain offers a compelling case in point. Under the Basque Economic Agreement, rooted in Spain’s 1978 Constitution, the 1979 Statute of Autonomy, and the Economic Agreement Law of 1981, tax collection powers have been devolved to the Basque territories. (Ituna Center for Basque Economic Agreement and Fiscal Federalism Studies, 2021[1]). Biscay collects all major taxes independently and finances its own public services, while remitting an annual quota (fixed at 6.24% of Spain’s general state expenditures) to the central government. This arrangement creates a high-stakes incentive structure: the province assumes full fiscal risk with no routine transfers from Madrid. Any shortfall in tax collection directly threatens public service delivery.
BATUZ is a comprehensive digital initiative launched by the Provincial Council of Biscay that integrates certified electronic invoicing, real-time economic data reporting, and proactive government services into a single compliance ecosystem (Provincial Council of Biscay, 2023[1]). It applies to all companies and self-employed persons subject to Biscay’s tax regulations regardless of size. Voluntary adoption opened on 1 January 2022 with tax incentives including reductions of up to 15% on the tax base for early adopters. Mandatory implementation began on 1 January 2024 for large companies, with smaller enterprises, self-employed workers, and non-profit entities being incorporated progressively, a rollout expected to be completed during 2026 (Provincial Council of Biscay, 2026[2]).
Rather than a standalone IT application, BATUZ presents an integrated framework of legal, technical, and service elements designed to transform tax compliance into a fully digital, end-to-end process. The system applies to all companies and self-employed individuals operating under Biscay’s fiscal jurisdiction and rests on three core pillars (Table 1):
TicketBAI, a certified e-invoicing software,
the Ledger of Economic Operations (LROE), a digital register of income and expenses,
automatic prefilling of tax returns with data held by the Provincial Treasury.
The interplay of these pillars supports a “compliance-by-design” environment. Real-time invoice authentication through TicketBAI and transaction reporting via the LROE in regular batches (up to four days after the transaction) provide the tax authority with a comprehensive suite of tools to enforce tax compliance, while the generation of prefilled draft returns can reduce administrative friction for taxpayers.
This case study analyses the BATUZ digital system through the lens of the OECD Digital Government Policy Framework (OECD, 2020[3]), which identifies six dimensions of a fully digital government initiative: digital by design, data-driven public sector, government as a platform, open by default, user-driven, and proactiveness. It does not assess Biscay’s tax policy, nor the impact of the BATUZ system on it.
BATUZ embeds digital processes in tax administration through its mandatory use: invoices that do not meet TicketBAI’s digital signing requirements cannot be legally issued. This shifts enforcement from ex-post audits to continuous, real-time digital monitoring integrated directly into everyday business operations (Provincial Treasury of Biscay, 2024[4]). Furthermore, the system’s open standards and application programming interfaces (APIs) ensure it is flexible and scalable as business technology and needs evolve.
From resilience and service continuity perspectives, BATUZ leverages the digital infrastructure, cybersecurity policies and technological support of Lantik, Biscay’s public company and IT service provider. Lantik has put in place policies, technology and measures to secure the continuity and reliability of BATUZ given its mission critical role in supporting Biscay’s tax administration (OECD, 2026[5]). Furthermore, the Provincial Council is prioritising the development and maintenance of BATUZ by investing 4M euros annually, with accumulated investments between 12M and 15M over a period of four years (Provincial Council of Biscay, 2021[6]).
Every invoice and expense record flows into the Provincial Treasury’s databases in near real-time, creating a continuous, structured data stream that can enable risk detection, automated cross-checks, and the generation of individualised draft tax returns (Provincial Council of Biscay, 2023[1]; Provincial Treasury of Biscay, 2024[4]). As a result, the administration functions as an always-on analytics platform, contributing to both proactive enforcement and responsive service delivery.
Biscay publishes open technical specifications and APIs, enabling dozens of private software providers to develop TicketBAI-compliant solutions. Simultaneously, the free Haz tu factura web application ensures that no taxpayer is excluded due to a lack of commercial software (Provincial Treasury of Biscay, 2024[4]). This dual-track approach harnesses private-sector innovation while guaranteeing inclusiveness.
While tax data are inherently confidential, BATUZ introduces an element of public transparency through QR codes printed on every invoice. Citizens can scan any receipt via the Comprueba tu factura portal to verify that a transaction has been duly reported to the tax authority (Provincial Treasury of Biscay, 2024[4]).
BATUZ was designed for the full spectrum of taxpayers. Key user-driven features include pre-filled tax returns, a phased rollout to progressively test, iterate and adopt the system (2018–2022), the free Haz tu factura tool for micro-enterprises. Anticipating that SMEs might face adoption challenges, Biscay also deployed transitional incentives and support ahead of the full entry into force through financial support to acquire the equipment and systems required to use BATUZ (Provincial Treasury of Biscay, 2024[4]). To capture and understand user needs, Biscay applied service design methodologies to involve users early in the design phase and throughout the development and operation of the system (OECD, 2026[5]).
The automatic generation of prefilled tax returns represents an important step for proactive tax returns and implementation of the once-only principle: the administration uses data that already holds to prepare draft tax declarations in advance to the formal tax declaration. Furthermore, the real-time approach to data collection can allow detecting inconsistencies to be flagged early on rather than through ex-post audits. (Provincial Council of Biscay, 2023[1]; Provincial Treasury of Biscay, 2024[4]).
After three years of implementation, results on adoption and use are promising. Nearly 70,000 individuals and entities have adopted the BATUZ system and used TicketBai and LROE since 2024 (90% of expected users), with most of them adhering voluntarily (Provincial Council of Biscay, 2026[2]). Consequently, digital invoicing through Haz tu fatura has multiplied eightfold in just four years (2022-2025), reaching approximately 1.9 million digital invoices (Provincial Council of Biscay, 2026[2]). Furthermore, the number of operations recorded in the LROE doubled annually between 2022 and 2024, and in 2025 exceeded 680 million entries.
Altogether, these developments are speeding up tax returns. The Provincial Council of Biscay commits to depositing tax refunds into the taxpayer's bank account within a maximum of seven days from the date the declaration is submitted. In practice, refunds typically arrive within 5 to 15 business day. This happens since the tax authority already has the taxpayer's invoicing and economic operations data through TicketBAI and the LROE, and therefore can pre-fill and cross-check returns much more quickly, which in turn enables faster processing of refunds (Provincial Council of Biscay, 2026[2]). Biscay’s provincial autonomy provided unique institutional advantages, the core principles can be extrapolated to other government processes: embed digital capability from the outset, encourage a proactive provision of services, and ultimately support effective reforms through and open and user-driven approach. Therefore, the BATUZ experience offers the following lessons to address the digital transformation of government processes:
Adopt a ‘Government as a Platform’ mindset: use and publication of open APIs and certification frameworks as well as the provision of free public tools provide a safety net for smaller users.
Embed transparency mechanisms. Features such as QR-based invoice verification can make the system more transparent and build public confidence in the reform.
Design with and for the user. Pre-filled returns, phased rollouts, and accessible tools are key for broad adoption, particularly among SMEs.
Provide direct incentives for technology adoption: financial support for SMEs IT investment can make regulatory compliance into a modernisation opportunity.
Phase implementation and provide proactive support. Pilots, voluntary adaptation periods, and early stakeholder engagement reduce friction, enable adoption and build institutional readiness.
References and further reading
[7] Ituna Center for Basque Economic Agreement and Fiscal Federalism Studies (2021), What is the Basque Economic Agreement? History, operation and quota.
[5] OECD (2026), Digital Government Review of Biscay, Spain, OECD Digital Government Studies, OECD Publishing, Paris, https://doi.org/10.1787/ab35c0ea-en.
[9] OECD (2021), The Digital Transformation of SMEs, OECD Studies on SMEs and Entrepreneurship, OECD Publishing, Paris, https://doi.org/10.1787/bdb9256a-en.
[3] OECD (2020), “The OECD Digital Government Policy Framework: Six dimensions of a Digital Government”, OECD Public Governance Policy Papers, No. 02, OECD Publishing, Paris, https://doi.org/10.1787/f64fed2a-en.
[8] OECD (2013), Electronic Sales Suppresion: A Threat to Tax Revenues, https://www.oecd.org/content/dam/oecd/en/publications/reports/2013/02/electronic-sales-suppression_f668c17b/f99b756d-en.pdf.
[2] Provincial Council of Biscay (2026), La Diputación Foral de Bizkaia culmina el proceso de incorporación a BATUZ, https://www.bizkaia.eus/es/web/comunicacion/noticias/-/news/detailView/la-diputacion-foral-de-bizkaia-culmina-el-proceso-de-incorporacion-a-batuz.
[1] Provincial Council of Biscay (2023), ¿Qué es Batuz?, https://www.batuz.eus/es/inicio.
[6] Provincial Council of Biscay (2021), BATUZ, https://web.bizkaia.eus/es/web/area-de-prensa/noticias/-/news/detailView/19269.
[4] Provincial Treasury of Biscay (2024), BATUZ – Haz tu factura, https://www.batuz.eus/es/haz-tu-factura.
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