The Cost of Filing

HMRC's Interest Restriction Return service was created to bring large corporations into compliance with new rules limiting how much tax relief companies can claim on interest and financing costs. Filing annually, users were corporate tax accountants working on behalf of the UK's largest companies – a specialist, time-pressured audience with little tolerance for inefficiency.

Framing the challenge

In the early stages of the service, tax professionals completed the return using a spreadsheet template – slow, but workable. Inefficiencies became more acute when accountants were managing returns across large volumes of companies.

To address this, HMRC formed an agile delivery team to understand the challenges faced by customers and build a digital solution within the strict constraints of the GDS framework.

What we did

Our team – user research, content design, interaction design, BA, developers, QA and scrum master – worked with HMRC's well-developed research participant pool to engage directly with commercial tax professionals. This gave us sustained, structured access to the people who would use the service throughout the design and build process.

What we found

• The existing spreadsheet approach represented a significant time commitment for accounting teams

• A GDS-compliant online form would increase, not decrease, that time commitment

• Accountants were concerned about the risk of human error when copying figures manually between platforms

• The commercial accounting sector was consistently clear: an API-only service was the preferred approach, allowing direct integration with existing software

Iterating the design

Throughout the research phase I continued to iterate the prototype alongside the content designer – refining copy, element types and form structure to reduce friction where possible. As additional requirements came in from HMRC leadership, however, the form grew to over 100 screens.

I briefed the team leads and project sponsor on the research findings and their implications for future uptake. The decision was taken to proceed as planned and carry the service through GDS assessment.

The outcome

When I completed my time on the project, the service was still intended to combine a webform with a later API integration. Following launch, and with further insights gathered in the field, HMRC decided to retire the webform and move to their current approach – a modified spreadsheet alongside an API solution that integrates directly with commercial accounting software.

The research had indicated this direction from an early stage.