Company Tax Return for Electricians: Your Complete Guide
Running an electrical business as a limited company means filing a company tax return with HMRC every year. This form — officially called the CT600 — reports your company's profits and calculates how much corporation tax you owe. This guide covers the key things electricians need to know: allowable expenses, capital allowances on tools and vans, the Construction Industry Scheme, and common mistakes to avoid.
Who Needs to File a Company Tax Return?
If you trade through a limited company, you must file a CT600 regardless of whether your company made a profit. Even in a loss-making year, the return is required.
Sole traders and partnerships do not file a CT600 — they use Self Assessment instead. This guide is for electricians operating through a limited company.
Key deadlines:
- File the CT600: 12 months after your accounting period ends
- Pay corporation tax: 9 months and 1 day after your accounting period ends
Corporation Tax Rates
Your company pays corporation tax on its taxable profits. The rate depends on the size of those profits.
| Profit level | Tax rate |
|---|---|
| Up to £50,000 | 19% (small profits rate) |
| £50,001 to £250,000 | Marginal relief applies |
| Over £250,000 | 25% (main rate) |
Source: GOV.UK — Corporation Tax rates
Note that if your company has associated companies — for example, you own shares in another limited company — the thresholds are divided between all associated companies.
Allowable Expenses for Electricians
Taxable profit is your income minus allowable business expenses. Getting your expenses right is one of the most important parts of the return.
Materials and consumables
Cable, conduit, junction boxes, consumer units, sockets, switches, and all electrical materials used on jobs are fully deductible. Keep purchase invoices and job records to support your claims.
Tools and equipment
Hand tools, power tools, test equipment (multimeters, insulation testers, PAT testers), and inspection kits all qualify as deductible business assets. Smaller tools can often be written off as direct expenses; larger items may suit capital allowances treatment (see below).
Van and vehicle costs
A van used solely for business is deductible in full: fuel, insurance, MOT, servicing, tyres, and road tax. If you use a personal vehicle for some business journeys, you can claim the approved mileage rate instead of actual vehicle costs.
Purchasing a van outright qualifies for the Annual Investment Allowance, allowing you to deduct the full purchase price from taxable profits in the year of purchase. See our capital allowances guide for the current AIA limit and how to claim.
Uniforms and PPE
Safety boots, hi-vis jackets, hard hats, and protective gloves worn on site are deductible. Regular clothing that you could wear outside work does not qualify.
Insurance
Public liability insurance, professional indemnity, employer's liability (if you have staff), and tool insurance are all allowable expenses.
Training and certification
Maintaining existing qualifications — updating to the latest edition of the wiring regulations, renewing NICEIC registration, first aid renewals — is deductible. Training that qualifies you in an entirely new discipline may not qualify.
Subcontractor costs
If you bring in other electricians as subcontractors, their invoices are deductible. Under the Construction Industry Scheme, you may also need to deduct tax from their payments before paying out.
Home office
If you use a space at home for quoting, invoicing, and administration, a proportion of home running costs — broadband, utilities — can be claimed against the business.
Capital Allowances
Capital allowances let you deduct the cost of business assets from your taxable profits. The key allowance is the Annual Investment Allowance (AIA), which permits a full deduction for qualifying plant and machinery in the year of purchase.
For electricians, AIA-qualifying assets typically include:
- Vans and commercial vehicles
- Power tools and specialist equipment
- Ladders, cable drums, and heavy kit
- Test and inspection instruments
- Computers and tablets used for the business
- Any equipment owned and used solely for work
If an asset has both personal and business use, only the business proportion attracts capital allowances.
The Construction Industry Scheme
Many electricians work as subcontractors on building sites and receive payments under the Construction Industry Scheme (CIS). CIS is designed so that tax is collected before profits reach your company.
Under CIS, the main contractor deducts tax from your gross payment before paying you:
- 20% if your company is registered as a CIS subcontractor
- 30% if not registered
On your CT600, you declare the total CIS deductions suffered during the year as a credit against your tax liability. If the total deductions exceed your corporation tax bill, HMRC refunds the difference.
Always collect your CIS statements. Missing them from your return means paying tax twice. If a contractor fails to issue them, chase immediately — they are legally required to provide monthly statements.
If your company acts as a main contractor and pays subcontractors, you must register as a CIS contractor and deduct the appropriate amounts from their payments.
For the wider construction industry context, see our CT600 guide for construction companies.
Common Mistakes to Avoid
Not claiming CIS deductions. This is the most expensive error electricians make. If contractors deducted CIS tax and you do not declare it on the CT600, you pay the same tax twice.
Missing capital allowances. Specialist test equipment, vans, and power tools can be substantial purchases. Claiming AIA on these reduces your taxable profit directly and is often the most significant tax saving available.
Mixing personal and business expenses. Anything personal paid through the company must be accounted for — either removed from expenses or treated as a benefit in kind. Keep business and personal spending clearly separated from the start.
Missing the payment deadline. Corporation tax is due 9 months and 1 day after your accounting period ends — three months before the filing deadline. Set a reminder for the payment date as well as the filing date.
Incorrectly treating vehicle costs. If the company owns a car, it cannot be claimed through the Annual Investment Allowance. Vans and cars are treated very differently in the tax rules, so classify your work vehicle correctly from day one.
See our CT600 common mistakes guide for additional pitfalls that apply to all limited companies.
Summary
Filing a company tax return as an electrician follows the same framework as any limited company, but there are trade-specific elements that make a real difference to your tax bill: CIS deduction credits, capital allowances on tools and vans, and correctly claiming all allowable business expenses. Get these right and you will pay the correct amount of corporation tax — nothing more.