5 Things HMRC Doesn't Actually Care About — and 3 It Really Does

Many UK business owners lose sleep over things that HMRC either does not care about or handles far more reasonably than people fear. At the same time, a few genuine triggers for HMRC attention go largely unnoticed until it is too late. This article addresses both honestly.

5 Things HMRC Doesn't Actually Care About

1. Round Numbers on Your Tax Return

There is a persistent myth that rounding expenses to the nearest pound — or that certain round numbers — trigger an HMRC enquiry. It does not. HMRC's systems look for statistical anomalies and implausible patterns, not round numbers. If your broadband costs approximately £50 a month, claiming £600 for the year is entirely reasonable and will not cause any interest.

2. Working From Home

Claiming home working expenses is a legitimate and common deduction. HMRC publishes flat rates precisely to make it easy (see our expenses article). There is nothing suspicious about a sole trader or director claiming a proportion of their home costs. What HMRC looks for is disproportionate claims — claiming 80% of your home costs when you clearly also live there — not the existence of the claim itself.

3. A Loss in One Year

Making a trading loss in a particular year does not automatically flag your return for review. Businesses have fluctuating profits. Losses can be carried back against prior year profits or forward against future profits. What draws attention is persistent losses over many years with no apparent business reason, or losses that seem implausibly large relative to the size of the business.

4. Having Multiple Income Sources

Reporting employment income, rental income, dividend income, and self-employment income on a single Self Assessment return is entirely normal and expected. HMRC's systems are built for exactly this. The complexity of your return does not increase your enquiry risk. Accuracy does.

5. Filing Close to the Deadline

Filing your Self Assessment return on 30 January is not a red flag. Millions of returns are filed in the final week before the 31 January deadline. What matters is that you file on time and the figures are correct. Filing early does not reduce your chances of an enquiry, and filing late (after the deadline) simply results in automatic penalties.

3 Things HMRC Really Does Care About

1. Lifestyle That Doesn't Match Declared Income

HMRC has sophisticated data-matching capabilities. If the lifestyle visible from property records, Companies House, social media, and other sources appears inconsistent with the income declared on your tax return, it can trigger a compliance check. This is one of the most common reasons for HMRC investigations into small business owners. Keeping your declared income consistent with your actual standard of living — and being able to explain any apparent inconsistency — is important.

2. Consistently Under-Reporting for Your Sector

HMRC holds benchmarking data for hundreds of business sectors. They know, statistically, what gross margins, expense ratios, and profit levels look like for businesses of different sizes in different industries. If your figures are significantly below the sector average year after year, your return may be selected for review. This does not mean you have done anything wrong — but it means being prepared to explain unusual figures.

3. Significant Changes Without Apparent Explanation

A business that has declared a consistent profit for several years and then suddenly declares a large loss, or a sole trader whose turnover doubles one year and halves the next without any obvious business reason, may draw HMRC's attention. This is not to say these things cannot happen — they can and do — but being able to explain significant changes with contemporaneous evidence (new contracts won, a major client lost, a difficult trading year) is important.

What to Do if HMRC Opens an Enquiry

Receiving an HMRC enquiry notice is stressful, but it is important to know that an enquiry is not the same as an accusation of fraud. Many enquiries are routine and resolve without any additional tax being owed. The key steps are:

• Do not respond to HMRC directly without speaking to your accountant first
• Gather your records — bank statements, receipts, invoices — for the period under review
• Do not destroy or discard any records, even if they seem unhelpful
• Be cooperative and respond to HMRC's questions accurately — evasiveness is counterproductive

At Ledgertech, we handle HMRC correspondence on your behalf as part of our service. If you receive an enquiry notice, contact us immediately.