Most self-employed electricians are confident wiring a consumer unit but far less sure what to do when a tax deadline arrives or a CIS deduction appears on an invoice. This guide walks through self assessment, CIS, VAT, allowable expenses, and what Making Tax Digital means for your electrical business in plain, practical terms.

Why getting your accounts right matters for electricians

When you work as a self-employed electrician or run a small electrical contractor business, you are responsible for your own tax from day one. That means filing a Self Assessment tax return each year, paying Income Tax and Class 4 National Insurance on your profits, and keeping records that can withstand an HMRC review. The personal allowance sits at £12,570, so the first slice of profit is tax-free, but everything above that is taxable at rates that rise quickly as your earnings grow.

Many electricians also work under the Construction Industry Scheme (CIS), where a contractor deducts 20% from the labour portion of your invoice before paying you. That deduction is not a final tax bill. It is a payment on account that you recover or offset when you file your Self Assessment return. Getting this process wrong, or missing the deduction entirely in your records, is one of the most common and costly errors we see.

Where most electricians go wrong with their accounts

The mistakes that cost electricians money are usually not dramatic. They are quiet, repeated oversights: not separating business and personal spending, invoicing for materials and labour as one lump sum under CIS, and missing allowable expenses that reduce a tax bill legally. None of these errors signal dishonesty, but all of them leave money on the table or create problems when HMRC asks questions.

Splitting materials and labour incorrectly on CIS invoices

Under CIS, the 20% deduction applies only to the labour element of an invoice, not to materials you supply. If you invoice for a combined total without separating the two, contractors will sometimes deduct 20% from the whole amount, costing you money. Equally, if you separate them incorrectly, HMRC can challenge the split on audit. Your invoices should clearly state labour costs and materials costs as separate line items every time.

Missing allowable expenses that reduce your tax bill

HMRC allows electricians to claim a wide range of business expenses against profits, including test equipment, hand and power tools, consumable materials, van costs, calibration of test equipment, NICEIC or NAPIT scheme membership, certification software, PPE, public liability insurance, phone and broadband costs, training, and accountancy fees. The Annual Investment Allowance (AIA) also lets you deduct the full cost of major equipment purchases in the year of purchase, up to £1,000,000. Many electricians we work with have never claimed half of what they are legally entitled to.

What to do: a step-by-step approach

You do not need to become an accountant to run a compliant electrical business. You need a clear sequence of actions and someone to handle the filings. The steps below cover the fundamentals that every self-employed electrician or electrical contractor needs to have in place.

1. Register for Self Assessment with HMRC as soon as you start self-employed work, or as soon as your income from self-employment exceeds £1,000 in a tax year. You will need a Unique Taxpayer Reference (UTR) to file returns and to register under CIS as a subcontractor. Do this early because delays in registration can result in late-filing penalties even if you owe no tax.
2. Open a dedicated business bank account and record every income and expense transaction each month. Keep your invoices, receipts, and bank statements in one place, whether that is a folder on your phone or accounting software. The habit of recording monthly rather than scrambling at year-end is the single change that makes the biggest difference to how much stress you carry into January.
3. Check your rolling 12-month turnover every quarter against the £90,000 VAT threshold, decide whether the mileage rate (45p per mile for the first 10,000 business miles, then 25p per mile) or the actual cost method suits your vehicle use better, and review whether you need to update your CIS registration status if you move between contractor and subcontractor roles. If your self-employment income is above £50,000, Making Tax Digital for Income Tax applies from April 2026, which means quarterly digital submissions to HMRC rather than a single annual return.

Each of these steps is straightforward on its own. The difficulty is staying on top of all of them while running a busy electrical business. That is where having a fixed-fee accountant who responds the same day makes a practical difference to how much time you spend on paperwork versus how much time you spend on paid work.

What accounting actually costs for an electrician

The cost of accounting services for a self-employed electrician varies depending on whether you are a sole trader or a limited company and how much turnover you are handling. At STZ Accounting, the sole trader package starts at £150 plus VAT per month and covers bookkeeping, bank reconciliation, VAT returns, annual accounts, and your personal Self Assessment. For a limited company, packages start at £215 per month and include corporation tax, payroll, and management accounts. Every price is fixed before any work starts, so there are no surprise invoices at year-end.

How to get started with your accounting today

You do not need to have everything perfectly organised before asking for help. Most electricians who contact STZ Accounting arrive with a backlog of receipts and a rough sense of what they have invoiced. That is a normal starting point. The first step is a free 20-minute call where David reviews where you are and tells you exactly what needs doing and what it will cost, with no obligation to proceed.

• Gather your last 12 months of invoices and bank statements before the call. You do not need to have categorised anything. Just having the raw figures available means the conversation can be specific rather than general.
• Check your trailing 12-month turnover against the £90,000 VAT registration threshold and note whether any of your income came from CIS contractors. These two details shape which services you need and what your first filing deadlines will be.