The VAT threshold for businesses in the UK has stayed at £90,000 since April 2024, unchanged through both the Autumn 2024 and Autumn 2025 Budgets. However, this threshold is recalculated each month, not annually, which can catch high-growth businesses off guard.
For companies experiencing rapid growth, a particularly strong month could propel turnover above the £90,000 mark before annual accounts signal it. Once this happens, the 30-day clock for VAT registration begins, regardless of the founder’s awareness.
As businesses grow quickly, so do their tax obligations. Increasing revenue each month also increases tax thresholds, filing requirements, and relief eligibility. By the time an accountant detects an issue, it may already have cost the business money—perhaps due to a missed VAT registration deadline, an incorrectly claimed relief, or an unexpected corporation tax bill.
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VAT Threshold Explained
The VAT threshold seems simple: surpass £90,000 in taxable turnover over a 12-month rolling period, and you have 30 days to register. However, it’s the ‘rolling’ aspect that trips up many founders. The House of Commons Library confirms the threshold has stayed at £90,000 since April 2024, unchanged through both the Autumn 2024 and Autumn 2025 Budgets, but the calculation resets every month rather than once a year.
For a fast-growing business, a particularly strong month could push turnover over the £90,000 line well before annual accounts would warn you. And once it does, the registration clock starts ticking, whether you notice or not.
Corporation Tax Bands Evolving
Currently, there are three effective corporation tax tiers: 19% for profits at or below £50,000, 25% above £250,000, and marginal relief tapering the rate in between. Founders who built their model around the 19% rate often don’t clock it when growth pushes them into marginal relief territory, or the full 25% band, until a year-end filing turns up with a much bigger bill attached.
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Running more than one company and the profit thresholds get split between them, which can pull a business into a higher effective rate sooner than a standalone forecast would suggest. Short accounting periods lower those thresholds further too, and that detail often doesn’t make it into early-stage planning.
R&D Tax Relief Under Scrutiny
Research & Development (R&D) tax relief is still one of the better reliefs available to scaling companies, but HMRC has cracked down hard on enforcement in recent years. Claims that would have sailed through a few years ago now get challenged far more often, and an incorrect claim doesn’t just cost the company that filed it. We covered this in R&D misclaims as a hidden risk for investors, which found that liability from a bad claim can follow a company well after the original filing, especially once investors show up and due diligence starts digging through old paperwork.