HMRC self-assessment campaign – why careful expense management matters
HMRC has made clear that it will be paying closer attention to self-assessment tax returns from 2024/25, with a sharp focus on whether taxpayers are wrongly claiming personal expenditure as business costs. This follows a trial digital campaign last year that brought in over £27 million in additional tax revenue, highlighting just how significant this area has become for the Treasury.
For sole traders, business partners, and landlords, this means increased scrutiny — and more enquiries — into how expenses are being allocated between personal and business use. At RPGCC, we believe this is a wake-up call that the best way to approach tax compliance is through planning ahead and ensuring that records and claims are watertight.
HMRC Self-assessment campaign – why is HMRC tightening its approach?
Tax relief is designed to support genuine business costs, but HMRC’s trial showed that many taxpayers were either misunderstanding the rules or being too generous in their interpretations. The “wholly and exclusively” rule is not new, but its application can often cause confusion — particularly where an expense has both business and private elements.
The government is under pressure to balance its books without raising headline rates of income tax for working people. As such, HMRC is expected to continue ramping up compliance activity and using digital tools to spot irregularities. The new HMRC self-assessment campaign is one way of making sure that additional revenue is collected without needing to change the law.
HMRC self-assessment campaign – common self-assessment pitfalls
At RPGCC, we frequently help clients untangle expense claims where the line between business and personal has become blurred. Some of the most common areas that cause problems include:
- Travel and subsistence – Everyday lunches are not deductible, but meals as part of an overnight business trip may be.
- Vehicle costs – Using one vehicle for both work and personal reasons requires accurate mileage logs.
- Use of home as office – A popular claim since the pandemic, but HMRC is alert to over-generous apportionments.
- Entertaining – Taking clients out for lunch may feel business-related, but it is rarely allowable for tax relief.
- Technology and phones – Mobile phone contracts or broadband bills often include personal use, which must be apportioned.
These are areas that highlight that “mixed use” expenses need careful consideration.
Why proactive planning makes all the difference
With the HMRC self-assessment campaign looming and HMRC stepping up enquiries, leaving claims unchecked until the tax return deadline is risky. Errors can lead to penalties of up to 100% of the lost tax and additional stress. By taking time to review expenses early in the tax year, taxpayers can:
- Correct inaccuracies in past returns before HMRC raises questions.
- Put systems in place — such as mileage logs or expense trackers — to support claims in future years.
- Ensure consistency in how mixed-use expenses are apportioned.
- Build confidence that their returns will withstand scrutiny.
Adam Thompson our Private Client Tax Partner at RPGCC, added “HMRC’s renewed focus shows how important it is to get the basics right. Expenses that are not supported by evidence or that have not been correctly apportioned are increasingly likely to be challenged. By planning ahead, our clients can avoid unnecessary disputes and ensure that they are not only compliant but also making the most of the reliefs legitimately available to them.”
Kay Merryman, RPGCC’s Head of Marketing added “This is also a good opportunity to remind clients that RPGCC offers a comprehensive Tax Investigation Service, supported by a trusted, market leading, third-party provider. This service gives clients peace of mind that, should HMRC open an enquiry into their affairs, our professional fees for assisting and defending their position will be covered by the scheme — even where, as is most often the case, the client has done nothing wrong. The reassurance and protection this scheme gives our clients should not be underestimated.”
HMRC self-assessment campaign – a fast-changing environment
What is particularly important to recognise is that HMRC is not standing still. The introduction of digital campaigns and data-driven compliance checks reflects a broader shift towards using technology to identify risk areas more quickly. This is part of a bigger move towards digital tax administration, and it will impact how businesses and individuals interact with the tax system over the next few years.
As compliance activity becomes more targeted, taxpayers who have robust systems and advice in place will be better protected. Those who leave their returns to the last minute may find themselves on the back foot if HMRC decides to open an enquiry.
How RPGCC supports clients with a HMRC self-assessment campaign
We work closely with clients — from sole traders to large businesses and property owners — to review expense claims, strengthen record-keeping, and anticipate how HMRC’s focus areas might apply to their situation. Our services include:
- Reviewing historic claims where there may be uncertainty.
- Advising on the best method of apportioning mixed-use expenses.
- Helping clients set up practical systems for tracking expenses in real time.
- Providing clarity on areas of grey, such as those listed above.
- Ensuring that any corrections are made in good time to reduce risk.
Our approach is always proactive. We don’t just prepare tax returns — we work with clients throughout the year to help them plan effectively, avoid surprises, and stay one step ahead of compliance changes.
HMRC self-assessment campaign – are you looking ahead?
The upcoming self-assessment period will be one of the most closely monitored in recent years. HMRC’s trial proved that tighter scrutiny can deliver significant results for the Treasury, so this trend is unlikely to reverse.
For taxpayers, the message is clear: take the time now to review your expenses and make sure everything stacks up. For businesses, landlords, and self-employed individuals alike, this is an opportunity to build better systems and strengthen financial discipline. This will become increasingly important as Making Tax Digital becomes phased in from April 2026.
At RPGCC, we are here to guide clients through the process — offering practical, tailored advice that balances compliance with efficiency. With the right planning, taxpayers can avoid costly mistakes and focus on what really matters: running their business and planning for the future.
If you have questions about how these developments might affect you, or if you’d like to arrange an expense review ahead of filing your 2024/25 return, please don’t hesitate to get in touch with our team.
