Small Businesses Now Drive 62% of the UK Tax Gap — What That Means for Compliance Checks

New figures show small businesses now account for the majority of the UK's "tax gap" — the difference between tax theoretically owed and what's actually collected — and HMRC's modernisation drive is increasingly aimed at closing it. Here's what the numbers mean and how to keep your business off HMRC's radar for the wrong reasons.

The numbers

Small businesses accounted for 62% of the total tax gap in 2024/25, while the specific VAT tax gap rose to 6.6% in 2024/25. This comes as HMRC pushes ahead with its annual Transformation Roadmap, published 2 July 2026, which the department describes as the most significant modernisation of the UK tax system in a generation.

The tax gap isn't just deliberate evasion — HMRC's own analysis has consistently found that a large share comes from errors, failure to take reasonable care, and the hidden economy, rather than criminal fraud. But the practical effect for small business owners is the same: rising tax gap figures tend to translate into more targeted compliance activity.

Why small businesses specifically

Smaller businesses are more likely to rely on manual bookkeeping, have less specialist in-house tax expertise, and operate across VAT, PAYE and Corporation Tax simultaneously — all factors that increase the chance of genuine error even without any intent to underpay. HMRC's digitisation push, including the ongoing rollout of Making Tax Digital, is explicitly framed as reducing this error-driven gap by removing manual re-keying and mismatched records.

Checklist: keeping your business compliance-ready

• Use MTD-compatible software for VAT and, where applicable, Income Tax records, rather than spreadsheets prone to transcription errors.
• Reconcile your VAT return against your actual sales and purchase ledgers each quarter, rather than relying solely on software-generated figures without a manual sense-check.
• Respond promptly to any HMRC "nudge letter" — these are increasingly used to flag discrepancies before escalating to a formal enquiry, and early engagement is treated more favourably.
• Keep evidence for every expense claimed, including for mixed-use costs like vehicles or home-working, since these remain a common source of compliance queries.
• Review your risk profile honestly — cash-heavy sectors (hospitality, trades, personal services) continue to receive proportionately more scrutiny.
• Use a registered agent or accountant for VAT and Corporation Tax filings if you don't have confidence managing them in-house; HMRC data consistently shows agent-filed returns have lower error rates.

Why this isn't just a UK issue

The UK's approach mirrors moves elsewhere: the US IRS has similarly focused enforcement resources on small business and self-employed segments in recent years, citing a disproportionate share of its own estimated tax gap, while Australia's ATO small business benchmarks programme flags businesses reporting income or expenses well outside industry norms for closer review.

Key Numbers

• 62% — share of the 2024/25 UK tax gap attributable to small businesses
• 6.6% — the VAT tax gap specifically in 2024/25
• 2 July 2026 — publication date of HMRC's latest Transformation Roadmap update

Sources

• Ross Martin: SME Tax Update 23 July 2026
• Kelmer: HMRC Transformation 2026 — what it means for businesses
• GOV.UK: Making Tax Digital

Educational content only — not financial advice.