How to Submit an R&D Tax Credit Claim to HMRC: A Step-by-Step Guide for 2026–27
Roughly 840,000 new companies were incorporated in the UK last year. That's more than 2,000 a day, every single day, including weekends. And yet, at the same time, millions of people are quietly building perfectly good businesses as sole traders and have absolutely no plans to incorporate. Both groups can't be entirely right — or entirely wrong. The truth, as it so often is with tax, sits somewhere in the numbers, not in the general advice you'll find on a forum at eleven o'clock at night.
I get asked this question more than almost any other: "Should I go limited?" It usually comes from someone who's had a good year, heard a friend mention "tax efficiency" at a barbecue, and is now lying awake wondering if they're leaving money on the table. Sometimes they are. Often, they're not — not yet, anyway. I remember a landscaper client from near Tonbridge who came to me convinced he needed to incorporate because his mate, a plumber, had done it and "seemed pleased with himself about it." When we actually ran his numbers, at his profit level, incorporating would have cost him more in accountancy and admin than it saved him in tax. He stayed a sole trader for another eighteen months, and when his profits genuinely grew past the point where it made sense, we made the switch properly, with a plan behind it rather than a hunch.
That's really what this guide is about — giving you the actual numbers for 2026–27, so you can make this decision with evidence rather than envy.
As a sole trader, you and your business are legally the same entity. There's no separation — the profits are your income, and the debts, if things go wrong, are your debts. A limited company is a completely separate legal person in the eyes of the law. It owns its own profits, it can be sued in its own name, and you, as director and shareholder, are — with a few important exceptions I'll come back to — shielded from its liabilities.
Frustratingly, "it depends" is the honest answer, and anyone who tells you otherwise without knowing your numbers is guessing. As a broad rule of thumb for 2026–27, once trading profits climb comfortably above roughly £40,000–£50,000 a year, a limited company structure often starts to produce a meaningfully lower overall tax bill. Below that level, the combined cost of corporation tax, dividend tax, and the extra admin frequently outweighs the saving. This isn't a fixed line in the sand — it shifts depending on your personal circumstances, other income, and how much you need to draw out of the business to live on — but it's a genuinely useful starting point for the conversation.
For a growing number of profitable, established businesses — yes. For someone just starting out, testing an idea, or running a modest side business alongside employment, often not. The dividend tax rise that took effect in April 2026 has narrowed the gap between the two structures somewhat, which is exactly why this is a question worth revisiting even if you looked at it two or three years ago and decided against incorporating. What was true then isn't automatically true now.
Not necessarily more — often just differently. A sole trader pays income tax on all their trading profit, at 20%, 40%, or 45% depending on the band, plus Class 4 National Insurance. A limited company pays corporation tax on its profit first, and then you, personally, pay tax again when you extract money from the company as salary or dividends. It's the double layer — corporation tax, then personal tax on extraction — that makes the comparison genuinely complicated, rather than a simple "one rate versus another."
At higher profit levels, generally yes, because dividends are taxed more favourably than income tax on the equivalent amount, and they carry no National Insurance at all. At lower profit levels, the corporation tax layer plus the cost of proper compliance — statutory accounts, a CT600 return, Companies House filings — can eat into or entirely erase that advantage. This is precisely why I sit down with clients and model both scenarios side by side using their actual numbers, rather than a generic rule that might not fit their business at all.
For the 2026–27 tax year, companies pay:
That marginal relief band catches out plenty of growing businesses. It creates a slightly counterintuitive result where the effective tax rate on each additional pound of profit within that £50,000–£250,000 band can actually exceed the 25% main rate — up to 26.5% on the margin — before easing back down once you're clearly above £250,000. If your company's profits sit within touching distance of £50,000, a well-timed pension contribution or piece of capital expenditure before your year-end can sometimes keep you under the threshold entirely.
Since 6 April 2026, dividend tax rates rose by two percentage points across the board, following the Autumn 2025 Budget. For 2026–27, the rates are:
The dividend allowance — the amount of dividend income you can receive entirely tax-free, regardless of your other income — remains at £500. That's a fraction of the £2,000 allowance that existed just a few years ago, which is worth remembering if you last reviewed your extraction strategy before 2023. Every director I speak to who last checked their numbers "a couple of years ago" is usually surprised by how much has shifted since.
Sole traders pay Class 4 National Insurance at 6% on profits between £12,570 and £50,270, and 2% above that. Class 2 National Insurance, once compulsory, is now voluntary for most sole traders below the small profits threshold, sitting at £3.65 a week for 2026–27 — worth paying voluntarily in some cases purely to protect your state pension entitlement, which is a detail people often overlook until it's too late to backfill easily.
This is where the comparison gets genuinely interesting. A limited company pays employer's National Insurance at 15% on salary paid above the £5,000 secondary threshold. That's a real cost the business bears, on top of whatever the director pays personally through employee NI at 8% on salary between the primary threshold and the upper earnings limit, and 2% above it. It's exactly why so many director-shareholders take only a modest salary — often set right around the personal allowance — and draw the rest of their income as dividends instead.
Dividends are a distribution of profit to shareholders, not earnings from employment, so neither employee nor employer NI applies to them at all. This is the single biggest lever behind the traditional "low salary, high dividends" strategy for company directors, and it's still meaningfully valuable in 2026–27, even after the dividend tax rise — just less dramatically so than it was five years ago. I had a client last year, a marketing consultant working with businesses across Kent and into London, genuinely startled to learn how much of her extraction strategy still made sense despite the changes, once we actually ran the comparison rather than assuming the old rules of thumb still applied unchanged.
Here's one that catches out even financially switched-on business owners. Once your adjusted net income exceeds £100,000, your personal allowance — normally £12,570 — starts reducing by £1 for every £2 you earn above that threshold, disappearing entirely once you reach £125,140. Combined with the 40% higher rate of income tax already applying in that band, the effective marginal tax rate on income between £100,000 and £125,140 works out at around 60%. That's a genuinely eye-watering rate on what, on paper, looks like a comfortably high income.
Both, equally. This trap isn't specific to one business structure; it applies to anyone whose taxable income — whether trading profit as a sole trader, or salary plus dividends as a director — falls within that band. I've seen sole traders genuinely surprised that incorporating alone wouldn't rescue them from it, because the trap follows total personal income, not the legal structure generating it.
Pension contributions are the most common and effective tool here, since they reduce your adjusted net income directly, potentially pulling you back below the £100,000 threshold and restoring your full personal allowance. Timing income across tax years, where genuinely possible, and — for company directors — adjusting the salary and dividend split, are other levers worth reviewing. This is a case where a twenty-minute conversation with your accountant before your year-end can be worth thousands of pounds, not an exaggeration I make lightly.
If your business runs into debt it can't pay, or faces a significant claim, your personal assets — your savings, potentially your home — are exposed. There's no legal wall between you and the business. For a freelance graphic designer with minimal contractual risk, that might be a perfectly acceptable position. For a builder taking on large contracts, or a consultant advising on high-value decisions, it's a genuinely different risk profile worth thinking about seriously.
As a director and shareholder, your personal liability is generally limited to the amount you've invested in the company — often just the nominal value of your shares. If the company fails owing money, your personal assets are, in normal circumstances, protected. This is one of the clearest, most tangible benefits of incorporation, and it's often the deciding factor for business owners even when the tax numbers alone wouldn't quite tip the scales.
Yes, and it's worth knowing where they sit. If you've personally guaranteed a loan or lease — which banks and landlords frequently require from small company directors — that protection doesn't extend to the guaranteed debt. And if a director is found to have acted fraudulently or continued trading while knowingly insolvent, the corporate veil can be pierced, exposing personal assets after all. Limited liability is real protection, but it isn't an unconditional shield.
Limited liability protection, often more favourable tax treatment at higher profits, a more "official" appearance to larger clients and lenders, and considerably more flexibility in how and when you extract income — which matters more than people expect when managing your own cash flow and tax planning. Company directors also have far more scope for structured pension planning through employer contributions.
A limited company must file statutory accounts and a confirmation statement with Companies House every year, on top of a corporation tax return (CT600) to HMRC. That's real, recurring admin — nothing a competent accountant can't handle smoothly, but it's meaningfully more than the single self-assessment return a sole trader submits.
As a broad guide across Kent and the South East, sole trader accountancy support often runs from £300–£700 a year for straightforward affairs. Limited company support, covering annual accounts, corporation tax, payroll, and Companies House filings, more typically runs from £1,000–£2,000 a year. That gap needs to be weighed honestly against any tax saving — which is precisely the calculation we walk clients through before recommending either route.
Once a year, covering the tax year running 6 April to 5 April, with the online filing deadline on 31 January the following year.
Increasingly, yes — though not everyone yet. Making Tax Digital for Income Tax became mandatory from April 2026 for self-employed individuals and landlords with qualifying income over £50,000, requiring quarterly digital updates plus a final annual declaration, rather than a single yearly return. It extends to those earning over £30,000 from April 2027. If your turnover is anywhere near these figures, this genuinely changes how you'll need to keep records — worth discussing well before it applies to you.
HMRC generally has four years from the end of the relevant tax year to assess additional tax owed where a genuine, reasonable-care error occurred — extending to six years for careless errors and twenty years for deliberate ones. It applies identically whether you're a sole trader or operating through a limited company; incorporating doesn't change how far back HMRC can look.
There's no strong evidence either structure attracts more scrutiny purely by virtue of its legal form. What genuinely raises HMRC's interest, in either case, are inconsistencies — income that doesn't match lifestyle, expense claims that look disproportionate, or figures that shift unexpectedly year on year. Clean, consistent records matter far more than which structure you've chosen.
The personal allowance for 2026–27 is £12,570, frozen at that level through to April 2031. Trading profit below that figure — after allowable expenses — isn't subject to income tax, though Class 4 National Insurance still applies once profits pass £12,570.
Take a sole trader with £40,000 of trading profit for 2026–27, no other income. Roughly £27,430 falls within the basic rate band and is taxed at 20%, giving income tax of around £5,486. Class 4 National Insurance adds 6% on profit between £12,570 and £40,000, around £1,646. Total tax and NI: roughly £7,132, leaving take-home profit of around £32,868. Run the same £40,000 through a limited company — small salary, remainder as dividends, after corporation tax and dividend tax — and the total often comes out fairly close, sometimes slightly better, sometimes slightly worse, depending on exact assumptions. It's genuinely this close at that profit level, which is why blanket advice in either direction so often misses the mark.
VAT registration becomes compulsory once taxable turnover exceeds £90,000 in any rolling 12-month period — a rule that applies identically whether you're a sole trader or a limited company. It's turnover, not profit, so a business with slim margins can cross this threshold faster than the owner expects.
As covered above, this is the headline change: quarterly digital reporting replacing the single annual return for sole traders and landlords above £50,000 qualifying income from April 2026, extending further from April 2027. It's a genuine shift in how record-keeping needs to work day to day, not just a filing technicality.
With the personal allowance frozen through 2031 while wages and profits generally rise, more sole traders drift into higher tax bands each year without any real-terms increase in income — a phenomenon economists call fiscal drag, and one worth factoring into any long-term planning.
The dividend tax rise from April 2026 is the other major shift specifically relevant to this comparison, narrowing — though not eliminating — the traditional tax advantage of incorporating at higher profit levels.
Often, yes, particularly with larger corporate clients or public sector work, some of which simply won't engage with unincorporated suppliers as a matter of procurement policy. I've watched Kent-based contractors win contracts specifically because incorporating made them eligible to even tender in the first place.
A limited company can issue shares, bring in investors, or be sold as a distinct legal entity in a way a sole trader business fundamentally cannot. If growth, investment, or an eventual exit is genuinely part of your plan, this is one of the strongest arguments for incorporating well before you actually need to.
A company builds its own credit history, separate from yours personally, which can matter considerably when applying for business finance, leasing equipment, or negotiating supplier terms — something that's simply not possible in the same way as a sole trader.
If your profits sit comfortably below £30,000–£40,000 and you don't have pressing liability concerns, the extra £700–£1,500 a year in accountancy and admin costs can easily outweigh any tax saving incorporating might offer.
Side businesses, early-stage ventures still finding their feet, and anyone testing an idea before committing fully are usually better served staying a sole trader until the numbers genuinely justify the switch.
If you value simplicity, plan to keep the business small and personal, or find the idea of statutory accounts and Companies House filings genuinely off-putting, there's nothing wrong with staying a sole trader indefinitely. Plenty of profitable, sustainable businesses across Kent do exactly that, by design rather than by accident.
The common approach for 2026–27 is a salary around the £12,570 personal allowance — using it efficiently against corporation tax as a deductible expense — with further income drawn as dividends. The exact optimal split shifts slightly each year as thresholds and rates move, which is exactly why this is worth reviewing annually rather than setting once and forgetting.
Employer pension contributions are generally deductible against corporation tax and, crucially, attract no dividend tax, income tax, or National Insurance at all — arguably the single most tax-efficient way to extract value from a profitable company, particularly for directors already comfortably above the higher-rate threshold.
Genuine business spending — equipment, tools, certain vehicles — brought forward before your company's year-end can reduce taxable profit for that period, sometimes usefully pulling profit back under the £50,000 small profits threshold.
There's no single universal number, but for most Kent-based sole traders we work with, the conversation genuinely becomes worth having once profits regularly exceed around £35,000–£40,000 a year — and it's worth revisiting annually after that, since thresholds and rates shift each tax year.
Is your profit level genuinely likely to stay above that threshold, or was this year an outlier? Do you need to withdraw most of the profit to live on, which reduces the dividend advantage, or can you leave some in the company? Does liability protection matter for your specific line of work? Is winning larger contracts or attracting investment part of your plan?
This is exactly the conversation I have with clients across Tunbridge Wells and the wider South East every single week. We don't work from rules of thumb pulled off the internet — we take your actual trading profit, your personal circumstances, and your plans for the business, and we model both routes side by side, with real 2026–27 figures, so you can see precisely what each path means for your take-home income before you commit to anything. Incorporating is straightforward to do and genuinely difficult to unwind cleanly once done, so it's worth getting right the first time.
If you're weighing up this decision, or simply haven't reviewed your structure since the dividend tax changes landed in April, get in touch. Or pop into the office — we'll run your numbers properly, and you'll leave the conversation actually knowing, rather than guessing.
Disclaimer:
The content of this blog is for general informational purposes only and should not be considered professional tax advice. The information is correct at the time of publishing but may change following future UK budget announcements or updates to HMRC guidance. Individual circumstances vary, and tax obligations can differ based on your personal situation. We strongly recommend consulting with us or a qualified tax professional to receive advice tailored to your specific needs.
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