Policy paper

HMRC’s external integration approach — enabling a thriving, innovative software market

Published 26 March 2026

1. Introduction and purpose

HMRC is committed, through the Transformation Roadmap, to enabling secure, modern, and innovative integration between third-party software and HMRC systems. While today this primarily occurs through Application Programming Interfaces (APIs), HMRC recognises that technology will continue to evolve. HMRC has always used APIs and they are currently HMRC’s preferred mechanism for integrating with HMRC systems, ensuring security, consistency, and a high-quality experience for customers and software providers.

Integration methods that attempt to automate or replicate HMRC’s web services, including screen scraping or automated browser interactions, are not supported. HMRC is aligning its approach with wider work on credential protection and eliminating unsupported access patterns.

This document sets out HMRC’s approach to external technical integration, providing detail on HMRC’s relationship and ways of working with software providers. The approach builds on HMRC’s longstanding ambition to make it easier for customers to meet their tax and customs obligations through the software products they already use and aims to respond to growing demands for increased data sharing from software providers that support UK growth. This document focuses on external APIs as they are the current core enabler of a thriving software market, contributing to HMRC’s strategic objectives to deliver a seamless, automated tax and customs system.

HMRC’s ambition is to design in partnership with stakeholders and is actively exploring opportunities, working with software providers, to innovate, expand and enhance the use of APIs.

This document sets out how HMRC intends to work with the software sector, reflecting a more collaborative, structured, and future-facing relationship. It forms part of HMRC’s strategic approach to third party software, which outlines the broader vision for HMRC’s partnership with the industry.

2. Background and context

In 2015, HMRC published its API Strategy, which set out the early direction for integrating with third party software. It outlined HMRC’s ambition and plans to make it easier for customers to use existing software to meet their tax and customs obligations without directly interacting with HMRC systems. This has streamlined the customer journey, reduced errors, and become the preferred method of submission and declaration across major regimes. Approximately 90% of digital returns in 2024 to 2025 were submitted via third party software, either directly by customers or through their advisers.

Over the last 10 years, the tax and customs system and how customers interact with it has changed. The integration of third party providers has also grown over this time, from around 600 to almost 3000 now. In the VAT service alone, the number of third party providers is over 1000 (up from 100). In 2024 to 2025, we received over 5.4 billion requests to these APIs, up from 4.1 billion in 2023 to 2024.

As the market has matured, software has become integral to how customers manage tax and customs obligations in their daily operations. More innovative products are being created in the market, helping businesses comply with the tax and customs system. Supporting these products with better external integration creates new opportunities to reduce administrative burdens, improve compliance, and enable richer products that help customers ‘get their tax right’.

External integration, specifically APIs, are a fundamental enabler for automation and integration across the tax and customs ecosystem, delivering transformation and setting the foundation for future modernisation. This strategic Approach supports the delivery of the Transformation Roadmap.

3. Vision for external integration

HMRC’s vision goes beyond APIs as a technical product. We aim to support software providers in building reliable, secure, and innovative services that integrate seamlessly with HMRC systems. This will further improve customer experience in the tax and customs system, help customers get their tax and customs obligations right, reduce the tax gap and enable software providers to innovate and compete on innovation, supporting a thriving third party market.

To achieve this, HMRC will:

• maintain an open and ongoing conversation with software providers to ensure evolving software products stay aligned with HMRC’s strategic ambitions
• align external integration with the strategic aims of HMRC’s strategic approach to third party software, including professionalising relationships, recognising market diversity, and enabling innovation

4. Principles for integration

This external integration approach is governed by many of the same guiding principles as HMRC’s strategic approach to third party software. Application of these principles may vary, recognising the differences and diversity of the software market and its customers.

Existing regime specific requirements, legal obligations and contractual arrangements, will continue to take precedence.

The following guiding principles apply directly to HMRC’s external integration approach.

Partnership and collaboration

Where reasonable and appropriate, external integration will be co-created with software providers, with open channels for feedback and proposals. HMRC and software providers share a common goal: enabling customers to interact with the tax and customs system easily, securely, and accurately. Our approach is therefore one of mutual partnership, balancing:

• HMRC requirements, such as adhering to standards that HMRC sets out on the software providers as well as their products, and supporting HMRC’s strategic objectives and other legal obligations
• developer opportunity, including better data access (where appropriate), richer functionality, and mechanisms for influencing HMRC’s integration approach

Innovation and integration

Notwithstanding major HMRC change programmes and transformation objectives, HMRC will, where possible, prioritise external integration, specifically APIs that enable richer capabilities. This could include pre-population, real-time updates, HMRC Assist submission feedback and secure multi-party communication.

HMRC will work with software providers on innovative proof of concepts to test  new ideas that push the ambition of transformation, informing HMRC strategic and investment choices, and enable market innovation in-line with HMRC’s requirements.

Assurance and oversight

We will also apply strengthened oversight and monitoring of API usage to ensure reliable performance, secure access, and responsible use.

This work will link closely with HMRC’s plan for strengthening standards for software that integrates with HMRC, as well as HMRC’s plan for software registration.

Customer empowerment

APIs will support accessible, reliable, and secure solutions for all customer segments, operating in tax and customs regimes. This includes ensuring customers have access to guidance at the point of need.

Integration methods that attempt to automate or replicate HMRC’s web services, including screen-scraping or automated browser interactions, are not supported. HMRC is aligning its approach with wider work on credential protection and eliminating unsupported access patterns.

5. Current landscape

HMRC recognises that external integration has historically developed in a programme-by-programme manner (such as Making Tax Digital). This will continue to drive programme and project external integration. However, there is a need for continuous improvement and a more coherent, long-term approach to wider external integration.

The significant growth in API usage and third party involvement demonstrates both demand and opportunity. Improved integration products, coupled with more structured engagement, will help software providers build the next generation of tax and customs technology, with benefits to customers and compliance. Currently, APIs are the preferred means of integrating with HMRC systems. This may develop as technology evolves and HMRC will review as needed.

6. HMRC’s approach

HMRC will expand and improve its integration offering, with a current focus on APIs, working closely with software providers to develop high‑quality, secure, and reliable integration products.

To create improved opportunities for co-creation with providers, HMRC will:

• establish an ‘API Innovation Portal’. This will provide a transparent mechanism for industry proposals on external integration (APIs), data access, and integration improvements. It will offer visibility of requests and progress in real time, increasing visibility and transparency of integration development. It will apply a standardised process for handling software provider requests for new data or functionality. responding to developer needs and include a searchable API catalogue organised by product and function

• Strengthen the minimum service standards for software that integrates via the HMRC Developer Hub, with a clearer focus on tax accuracy, customer protection, and the prevention of harm and apply to all integrated products

As new customer-facing services are developed, HMRC will ensure developers can participate early so that products are well aligned with user needs, including opportunities for testing and feedback before launch.

HMRC will also articulate clear policies for data sharing, balancing openness with robust security and compliance, and strengthen controls to prevent non-integrated third parties from accessing HMRC systems without oversight.

7. Next steps

HMRC will publish:

• a detailed delivery plan, as part of the broader delivery plan for ‘Strategic approach to third party software’ by Spring 2027, outlining upcoming improvements, new APIs, and migration expectations
• further information on the ‘API innovation portal’, including its initial functionality and developer engagement process
• clarified guidance on supported vs unsupported access methods, aligned with broader HMRC work on security and credential protection

8. Further reading

This document should be read alongside HMRC’s strategic approach to third party software, which sets the overarching vision and principles for HMRC’s partnership with the software sector.