Freelance Structural Engineer Tax UK 2026/27: Ltd Company, Salary and Dividends
Freelance structural engineers working through their own limited company face Corporation Tax, salary/dividend planning and IR35 risk on site-based contracts. Full worked example on £90,000 revenue shows exactly what's left after tax.
Limited company is the norm, but IR35 needs watching
Freelance and consultant structural engineers overwhelmingly trade through their own limited company rather than as sole traders — partly because construction clients expect it contractually, and partly because it opens up salary/dividend extraction, which is generally more tax-efficient than sole trader profit once earnings climb past £30,000-£40,000. The trade-off is IR35: if you're placed on a single construction site for months at a time, working hours set by the principal contractor, closely directed and unable to send a substitute engineer in your place, HMRC can treat that engagement as employment in substance and tax it accordingly — regardless of the limited company structure. Genuinely project-based work (producing a structural design package, running calculations for a defined scope, advising across several concurrent clients) sits much more comfortably outside IR35 than an extended, closely supervised site placement.
Corporation Tax Calculator
Calculate Corporation Tax for UK limited companies for 2025/26.
Open Corporation Tax calculatorWorked example: limited company, £90,000 revenue
Company revenue: £90,000 (structural design fees, site inspections, calculation packages across several construction clients)
Deductible company expenses:
- Structural analysis and CAD software licences (Tekla, StaadPro, AutoCAD): £4,200
- Professional indemnity insurance: £2,800
- ICE membership, CEng renewal and CPD courses: £600
- Accountancy, admin and general overhead: £5,400
- Total expenses: £13,000
Director's salary: £12,570 (set at the Personal Allowance/NI primary threshold)
Employer's National Insurance on salary above the £9,100 secondary threshold: (£12,570 − £9,100) × 13.8% = £479
Chargeable profit: £90,000 − £13,000 − £12,570 − £479 = £63,951
Corporation Tax (marginal relief, profit between £50,000 and £250,000):
- Tax at main rate: £63,951 × 25% = £15,987.75
- Marginal relief: (£250,000 − £63,951) × 3/200 = £186,049 × 0.015 = £2,790.74
- Corporation Tax payable: £15,987.75 − £2,790.74 = £13,197
That's an effective rate of roughly 20.6% on chargeable profit — well below the 25% main rate, thanks to marginal relief.
Profit after Corporation Tax available for dividends: £63,951 − £13,197 = £50,754
Corporation Tax Calculator
Calculate Corporation Tax for UK limited companies for 2025/26.
Open Corporation Tax calculatorExtracting the profit: salary plus dividends
Salary (£12,570): fully covered by the Personal Allowance, so £0 income tax. Since the primary threshold for employee National Insurance also sits at £12,570 for 2026/27, there's £0 employee NI either. The salary nets the full £12,570.
Dividends (£50,754 available):
- First £500 covered by the dividend allowance: taxed at 0%.
- Remaining taxable dividends: £50,754 − £500 = £50,254
- Basic rate band remaining above the salary (up to £50,270 total income): £37,700 taxed at 8.75% = £3,298.75
- Balance in the higher rate band: £50,254 − £37,700 = £12,554 taxed at 33.75% = £4,236.98
- Total dividend tax: £7,535.73
Net dividends: £50,754 − £7,535.73 = £43,218.27
Total personal take-home: £12,570 (salary) + £43,218.27 (net dividends) = £55,788.27
Dividend vs Salary Calculator
Compare taking income as salary vs dividends as a limited company director. See which method saves more tax in 2026/27.
Open Dividend vs Salary calculatorSalary vs dividends at a glance
| Salary route (all as salary) | Salary + dividend route (this example) | |
|---|---|---|
| Employer NI | Charged on full amount above £9,100 | Only on £12,570 salary (£479) |
| Corporation Tax relief | Full salary deducted before CT | Only £12,570 deducted before CT |
| Personal income tax | 20%/40% bands apply to full amount | £0 on salary; 8.75%/33.75% on dividends |
| Dividend allowance | Not applicable | £500 tax-free |
| Typical outcome | Higher combined tax | Lower combined tax for most profit levels |
The salary-plus-dividend split is the standard approach precisely because dividends aren't subject to National Insurance at all (employer or employee), and the dividend tax rates (8.75%/33.75%/39.35%) sit below equivalent income tax bands (20%/40%/45%). The gap narrows at higher profit levels but rarely disappears entirely.
Deductible company expenses checklist
- Structural analysis and CAD software: Tekla Structures, StaadPro, Robot Structural Analysis, AutoCAD
- Professional indemnity insurance (often a contractual requirement from clients)
- ICE membership, CEng/chartered status renewal, CPD courses
- Laptop and workstation hardware (Annual Investment Allowance for outright purchases)
- Accountancy and company secretarial costs
- Site visit travel and mileage
- Home office costs where design work is done outside client sites
Filing and paying
The company files a Corporation Tax return (CT600) and pays any Corporation Tax due within 9 months and 1 day of the end of its accounting period. As a director, you'll also file a personal Self Assessment return covering your salary and dividend income by 31 January following the tax year, even though most of the tax has already been settled at company level through Corporation Tax and PAYE on the salary.
Frequently asked questions
Should a freelance structural engineer trade through a limited company or as a sole trader?
Most freelance/consultant structural engineers use a limited company, partly because construction and engineering clients often expect it and partly because it allows salary/dividend extraction, which is usually more tax-efficient than sole trader income once profits rise above roughly £30,000-£40,000 a year.
Does IR35 apply to freelance structural engineers?
It can. If you're engaged for a long-term, site-based role where the client controls your hours, supervises your work closely and you can't send a substitute, HMRC may view the engagement as employment in substance (inside IR35), regardless of the limited company wrapper. Genuinely project-based, outcome-focused consultancy with multiple concurrent clients is much lower risk.
How much Corporation Tax does a structural engineering company pay on £90,000 revenue?
After typical expenses (software licences, PII insurance, ICE membership, admin) of around £13,000 and a director's salary of £12,570, chargeable profit is roughly £64,000. With marginal relief between the £50,000 and £250,000 thresholds, Corporation Tax comes to approximately £13,200 — an effective rate of around 20.6% rather than the full 25% main rate.
What's the most tax-efficient salary for a structural engineer running their own company?
A salary around the £12,570 Personal Allowance/NI primary threshold is the standard approach for 2026/27 — it uses up the tax-free personal allowance, keeps employee National Insurance at zero, and the salary itself is a deductible expense that reduces the company's Corporation Tax bill.
Is professional indemnity insurance essential for a freelance structural engineer?
Yes — it's typically a contractual requirement from construction clients and often a professional obligation under ICE membership terms, given the safety-critical nature of structural design work. It's a straightforward, fully deductible company expense.
Can a structural engineering company claim software licences like Tekla and StaadPro?
Yes, structural analysis and CAD software licences (Tekla Structures, StaadPro, Robot Structural Analysis, AutoCAD) are fully deductible business expenses, whether paid as an annual subscription or a one-off licence purchase, with one-off purchases also qualifying for the Annual Investment Allowance.
How much tax does £50,754 of dividends cost after salary and Corporation Tax?
Using the £500 tax-free dividend allowance and 2026/27 dividend rates, dividends taken on top of a £12,570 salary are taxed at 8.75% within the basic rate band and 33.75% above it. On £50,754 of dividends in the worked example, personal dividend tax comes to roughly £7,536, leaving around £43,218 net.
Do I need ICE membership as a freelance structural engineer, and is it deductible?
It's not a strict legal requirement to practise, but Institution of Civil Engineers (ICE) membership and chartered status (CEng) are near-universal expectations from clients and are fully deductible as a professional subscription, along with related CPD costs.
Should the company register for VAT?
Compulsory once taxable turnover exceeds £90,000 in a rolling 12-month period, which many structural engineering consultancies reach quickly given typical day rates. Since most clients are VAT-registered construction firms who can reclaim the VAT charged, voluntary early registration is often worth considering too, as it lets the company reclaim input VAT on software and equipment.
Try the calculators
Corporation Tax Calculator
Calculate Corporation Tax for UK limited companies for 2025/26.
Dividend vs Salary Calculator
Compare taking income as salary vs dividends as a limited company director. See which method saves more tax in 2026/27.
Contractor Take-Home Pay Calculator (IR35)
Compare take-home pay outside IR35 (Ltd), inside IR35 and umbrella for any UK day rate. Side-by-side 2026/27 breakdown.
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