For most field service business owners, year end accounting means handing a shoebox of receipts to an accountant and hoping for the best. It works, up to a point. But the businesses that find year end painful are almost always the ones that left the record-keeping until it became urgent.
This isn't a comprehensive accounting guide; your accountant handles the technical side. What it covers is the practical side: the deadlines, the records you need to have ready, the areas specific to field service that often catch people out, and the mistakes that tend to cost the most.
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A limited company doesn't follow the 5 April personal tax year. Your deadlines are set by your company's accounting year end, which you can find on Companies House.
Here's what you're working towards:
One important update: from April 2026, HMRC's old online filing service for company tax returns closes. All CT600 submissions will need to go through commercial software. If you're not already using an accountant or software to file, this needs sorting before then. HMRC has guidance on the transition here.
Before anything else, your bookkeeping needs to be complete for the year. An accountant can only work with what you give them. Gaps or errors in your records mean extra time, extra questions, and usually a bigger bill.
Work through this before you hand anything over:
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If you pay employees, including yourself as a director, there are separate payroll obligations that follow the 5 April tax year, regardless of when your company year end falls.
Missing the P11D deadline costs £100 per 50 employees for each month late. It's an easy one to forget because it falls in July, well after the rest of the year-end activity.
If your business operates in construction, fire and security, mechanical and electrical, or any sector where you pay subcontractors for labour on site, the Construction Industry Scheme (CIS) applies.
The problem most businesses run into: they don't track CIS suffered month by month, don't submit EPS correctly, and then find at year end they've either overpaid tax or missed the window to reclaim. HMRC estimates around £200 million in CIS refunds go unclaimed each year.
If CIS applies to your business, make sure your accountant is reconciling it throughout the year, not just at year end.
Most field service businesses have more deductible costs than they realise. These reduce your taxable profit, so it's worth making sure nothing is missed.
Commonly claimed and often overlooked in field service: vehicle costs (fuel, repairs, insurance, though not personal commuting), tools and equipment, work clothing and PPE, materials used on jobs, subcontractor costs, insurance, phone and data costs proportional to business use, training directly related to the work, accountancy fees, and software subscriptions including job management tools.
Business entertaining, such as taking clients out for dinner, is not deductible. HMRC's rule is that expenses must be wholly and exclusively for business purposes. If you're unsure whether something qualifies, ask your accountant before claiming it, not after.
One to watch: personal spending through the company. Putting non-business costs through the company and calling them expenses is one of the most common reasons HMRC opens an investigation. If a claim can't be justified with a receipt and a clear business reason, it shouldn't be in the accounts.
Most of the friction at year end comes down to records. If job sheets aren't signed off, invoices aren't matched to jobs, or materials costs haven't been logged, someone has to piece it together. That someone is usually you, the week before the deadline.
Fieldmotion keeps job records, labour time, materials, and invoicing in one place throughout the year. When year end arrives, the information your accountant needs is already there: completed jobs, costs attached to each one, invoices raised and paid.
That matters for CIS too. If you need to reconcile what you've paid subcontractors and what deductions were made, clean job-level records make that process considerably faster.
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When does a limited company's year end fall?
It depends on when your company was incorporated and whether you've changed it. By default, Companies House sets your year end as the last day of the month in which you incorporated. You can find your current year end date by searching for your company on the Companies House register. Many businesses align their year end to 31 March to roughly mirror the personal tax year.
What's the difference between my company year end and the tax year end?
The UK personal tax year runs from 6 April to 5 April. Your limited company has its own accounting year end, which can fall on any date. Payroll obligations (P60s, P11Ds) follow the 5 April tax year. Corporation tax and company accounts follow your company's year end.
Do I need to worry about Making Tax Digital?
MTD for Income Tax (MTD ITSA) applies to sole traders and landlords, not limited companies. Limited companies are already required to file corporation tax returns digitally. The main change coming is that HMRC's old CT600 online filing service closes in April 2026, so all company tax returns will need to go through commercial software from that point.
What records does HMRC expect me to keep?
You're required to keep business records for at least 6 years from the end of the accounting period they relate to. This includes invoices, receipts, bank statements, payroll records, and any CIS deduction statements if the scheme applies to your business.