Accountants for Plumbers & Tradespeople: What They Do, Cost & Why You Need One

Plumbers, electricians, and other tradespeople working as subcontractors on construction sites get pulled into the Construction Industry Scheme — a system with its own deduction rules — on top of the usual van, tools, and materials expenses any trade business claims. Add in the VAT domestic reverse charge for construction services, a VAT registration threshold that catches out growing businesses, and capital allowances on equipment that often go unclaimed, and it’s easy to see why generic small business accounting doesn’t quite fit a trade.

This guide sets out what an accountant for tradespeople actually does, how CIS, VAT, and equipment tax relief work in practice, and where subcontractors most often leave money unclaimed. It applies whether you’re a plumber, electrician, builder, roofer, decorator, or any other tradesperson working through construction subcontracting.

Quick Answer

An accountant for plumbers and tradespeople specialises in the tax issues specific to construction subcontracting: CIS registration and refund claims, the VAT domestic reverse charge, VAT registration once turnover crosses the threshold, and van, tool, and materials expense claims — including capital allowances on larger equipment purchases. It isn’t a legal requirement, but CIS deductions are taken on gross invoice value before expenses are considered, which means most subcontractors are owed a refund they’d otherwise miss without a proper Self Assessment review.

Key Takeaways

• Registered CIS subcontractors have 20% deducted at source; unregistered subcontractors have 30% deducted.
• CIS deductions are advance payments toward your tax bill, not the final amount — many subcontractors are due a refund.
• The VAT domestic reverse charge, in place since March 2021, shifts VAT accounting from subcontractor to contractor on most construction work.
• You must register for VAT once your taxable turnover crosses the current threshold — currently £90,000 in any rolling 12-month period.
• Tools and equipment above a certain value can often be claimed in full through the Annual Investment Allowance, not just as a small annual expense.
• Typical fees range from £180 to £500 depending on complexity and business structure.

Table of Contents

1. What Is an Accountant for Tradespeople?
2. What Does an Accountant for Tradespeople Actually Do?
3. CIS Deductions: How Much Tax Comes Off Your Invoices
4. The VAT Domestic Reverse Charge for Construction
5. VAT Registration: When You Cross the Threshold
6. Van, Tools & Equipment: Expenses and Capital Allowances
7. Sole Trader vs Limited Company for Tradespeople
8. Do You Actually Need One?
9. How Much Does an Accountant for Tradespeople Cost?
10. Accountants for Tradespeople in London
11. Common Mistakes People Make
12. Accountant Insights: What We See in Practice
13. Should You Hire One? (Decision Framework)
14. DIY vs Specialist Trade Accountant
15. Checklists
16. FAQs
17. Sources
18. Final Thoughts

What Is an Accountant for Tradespeople?

An accountant for tradespeople works specifically with the financial patterns of construction subcontracting: CIS deductions taken at source, the VAT domestic reverse charge, the point at which VAT registration becomes compulsory, and the mix of van, tool, and materials expenses that make up most of a trade business’s costs. General small business bookkeeping often misses the CIS refund opportunity entirely, since it requires reconciling deductions already taken against a properly calculated tax liability — and it just as often misses capital allowances on larger equipment purchases, which fall outside the pattern of everyday expense claims.

This applies whether you’re a sole trader plumber working under a handful of contractors, an electrician running a small team, or a builder who’s grown into subcontracting other tradespeople yourself.

What Does an Accountant for Tradespeople Actually Do?

• CIS registration — getting you set up correctly to avoid the higher unregistered deduction rate, and making sure your UTR is provided to every contractor you work for.
• CIS refund claims — reconciling deductions already taken against your actual tax liability once expenses are accounted for.
• VAT domestic reverse charge compliance — confirming which jobs the reverse charge applies to and invoicing correctly.
• VAT registration and returns — monitoring your rolling 12-month turnover and registering before you’re legally required to, avoiding a last-minute scramble.
• Vehicle, tool, and equipment expense tracking — applying the mileage rate or actual costs method consistently, and identifying when a purchase qualifies for capital allowances rather than a simple expense claim.
• Self Assessment or limited company accounts — depending on how your trade business is structured.

CIS Deductions: How Much Tax Comes Off Your Invoices

The gap between 20% and 30% is one of the most common and most easily fixed reasons subcontractors lose money unnecessarily. Registering for CIS as soon as you start subcontracting avoids paying an extra 10% that simply didn’t need to be deducted. See our dedicated CIS Accountant guide for the full mechanics of the scheme.

Illustrative Example: A self-employed electrician invoicing £45,000 a year to contractors, but never registering for CIS, would have 30% deducted at source — £13,500 — instead of the 20% (£9,000) a registered subcontractor pays. That’s £4,500 sitting with HMRC for months longer than necessary, even though it’s eventually credited against the final tax bill once a Self Assessment return is filed.

The VAT Domestic Reverse Charge for Construction

Since March 2021, most construction services between VAT-registered businesses use the domestic reverse charge, which shifts responsibility for accounting for VAT from the subcontractor to the contractor. In practice, this means subcontractors often don’t charge VAT on these invoices at all — the invoice should state that the reverse charge applies, and the contractor accounts for the VAT instead. Getting this wrong in either direction can lead to VAT return errors that need correcting later.

VAT Registration: When You Cross the Threshold

Separately from the reverse charge, every VAT-registered or soon-to-be-registered tradesperson needs to track their turnover against the compulsory VAT registration threshold — currently £90,000 in any rolling 12-month period, not just the tax year. This is a rolling calculation, so it’s possible to cross the threshold partway through a tax year without realising it, particularly during a busy few months.

Once you’re required to register, you must do so within a set timeframe or risk penalties, and from that point the domestic reverse charge rules described above start applying to your qualifying construction invoices. A specialist accountant typically monitors this on your behalf, flagging when you’re approaching the threshold well before it becomes urgent — voluntary early registration can sometimes make sense too, particularly if most of your customers are VAT-registered contractors who can reclaim the VAT you’d charge them.

Van, Tools & Equipment: Expenses and Capital Allowances

Day-to-day costs like fuel, small tools, materials, and protective equipment are generally allowable against self-employment income as they’re incurred. For vehicle costs specifically, you can choose between the mileage rate method or claiming actual costs (fuel, insurance, servicing, depreciation), but once you’ve chosen a method for a given vehicle, HMRC expects it to be applied consistently rather than switched between years.

Larger equipment purchases — a new van, a significant tool upgrade, diagnostic or specialist trade equipment — are often treated differently. Rather than trickling through as a small annual expense, qualifying purchases can frequently be claimed in full in the year of purchase through the Annual Investment Allowance, which can make a meaningful difference to that year’s tax bill. This is one of the most commonly missed reliefs among tradespeople who manage their own books, simply because it isn’t an obvious or intuitive category compared to a fuel receipt or a materials invoice.

Illustrative Example: A plumber who purchased £12,000 of new equipment and a van upgrade over two years, but claimed it only through standard depreciation rather than the Annual Investment Allowance, would have spread that tax relief out over several years instead of claiming it in full against the year the equipment was actually bought — delaying real cash flow benefit that could have been used immediately.

Sole Trader vs Limited Company for Tradespeople

Many tradespeople start out as sole traders, since it’s the simplest way to begin taking on subcontract work. As income grows, though, moving to a limited company structure often becomes worth reconsidering:

There’s no single right answer — it depends on your income level, growth plans, and appetite for extra admin. This is exactly the kind of decision worth reviewing with an accountant before making the switch, rather than after.

Do You Actually Need One?

• You’re registered for CIS but have never checked whether you’re due a refund.
• You work across both reverse-charge and standard-VAT jobs and aren’t confident which applies to each.
• Your turnover is approaching the £90,000 VAT threshold and you’re not sure when you’ll need to register.
• You’ve bought significant tools, a van, or equipment recently and aren’t sure whether it qualifies for capital allowances.
• Your van, tool, and materials expenses aren’t tracked consistently through the year.
• You’re considering moving from sole trader to a limited company structure.
• You’ve received a CIS-related query or penalty notice from HMRC.

How Much Does an Accountant for Tradespeople Cost?

Accountants for Tradespeople in London

London’s construction and trades sector is large and fast-moving, with plumbers, electricians, and builders regularly working across several sites and contractors within the same month. That pace makes it easy to lose track of which jobs fall under the domestic reverse charge, and easier still to cross the VAT registration threshold mid-year without noticing, given how quickly turnover can build up on London-scale projects and day rates.

London tradespeople are also more likely to be weighing up the sole trader versus limited company decision earlier in their careers, simply because average earnings and job values tend to run higher than the UK average — which means the tax efficiency gap between the two structures becomes relevant sooner. A specialist accountant familiar with how London’s construction supply chains and pricing typically work can usually spot a missed CIS refund, an overlooked capital allowance, or an approaching VAT threshold faster than a general practice unfamiliar with trade-specific patterns.

Common Mistakes People Make

1. Not registering for CIS before starting subcontract work
Why it happens: New subcontractors sometimes aren’t aware registration exists, or assume it happens automatically through the contractor.
Consequence: Deductions are taken at 30% instead of 20%, an avoidable extra cost on every single payment.
How to avoid it: Register for CIS with HMRC before invoicing your first contractor.

2. Losing track of CIS deduction statements
Why it happens: Subcontractors working for multiple contractors receive separate paperwork from each one, which is easy to misplace.
Consequence: An inaccurate or understated refund claim, since your Self Assessment relies on these being reconciled correctly.
How to avoid it: Keep every CIS deduction statement in one place as it’s received.

3. Applying VAT incorrectly under the domestic reverse charge
Why it happens: The reverse charge rules can be confusing when a subcontractor works across both reverse-charge and standard-VAT jobs.
Consequence: Incorrect VAT returns, which HMRC can query and which may need correcting after the fact.
How to avoid it: Confirm on each job whether the domestic reverse charge applies before invoicing.

4. Missing the VAT registration threshold without noticing
Why it happens: Because it’s a rolling 12-month calculation rather than tied to the tax year, turnover can quietly cross £90,000 mid-year during a busy period.
Consequence: Late VAT registration can trigger penalties and backdated VAT liability.
How to avoid it: Track rolling turnover monthly, not just at year-end, especially during growth periods.

5. Claiming equipment as a standard expense instead of a capital allowance
Why it happens: A large tool or van purchase can be mistaken for an ordinary running cost rather than a capital item.
Consequence: Tax relief gets spread out over several years instead of being available in full against the year of purchase.
How to avoid it: Flag any significant equipment or vehicle purchase to your accountant separately from routine expenses.

6. Switching between mileage rate and actual costs inconsistently
Why it happens: It can be tempting to pick whichever method looks better each year.
Consequence: HMRC requires consistency once a method is chosen for a given vehicle, and switching incorrectly can trigger a query.
How to avoid it: Choose one method per vehicle and apply it consistently throughout its use in the business.

Accountant Insights: What We See in Practice

• CIS refunds are the single biggest thing we help tradespeople recover — most subcontractors have no idea how much is sitting unclaimed until their return is properly prepared.
• The 20% vs 30% CIS registration gap is one of the easiest wins in construction accounting, and it costs nothing to fix.
• Capital allowances on tools and vans are consistently under-claimed among tradespeople who manage their own books, largely because equipment purchases don’t feel like a “tax” decision at the point of sale.
• The VAT threshold catches growing trade businesses more often than established ones — a sudden run of high-value jobs can push turnover past £90,000 faster than expected.
• The domestic reverse charge trips up more experienced tradespeople than new ones, because it changed how invoicing works partway through many people’s careers.

Should You Hire an Accountant for Tradespeople?

Step 1: Check your CIS registration status. If you’re not registered, this is the first and easiest thing to fix.

Step 2: Review whether you’re likely owed a refund. Most active subcontractors with genuine expenses are.

Step 3: Confirm your reverse charge and VAT threshold position. Get clarity on which of your jobs are affected, and how close you are to compulsory registration.

Step 4: Flag any significant equipment purchases. Make sure capital allowances aren’t being missed on vans or tools.

Step 5: Weigh the fee against the likely refund and reliefs. For most subcontractors, the value recovered outweighs the cost of the service.

DIY vs Specialist Trade Accountant

Checklists

Checklist 1: For Subcontractors

• ✓ Confirm you’re registered for CIS at 20%, not 30%
• ✓ Keep every CIS deduction statement from each contractor
• ✓ Track van, tools, and protective equipment costs throughout the year
• ✓ Flag larger equipment or van purchases separately for capital allowances
• ✓ File your Self Assessment to claim any refund owed

Checklist 2: VAT & Business Growth

• ✓ Track rolling 12-month turnover against the £90,000 VAT threshold
• ✓ Confirm which jobs the domestic reverse charge applies to
• ✓ State the reverse charge clearly on affected invoices
• ✓ Keep vehicle expense method consistent year to year
• ✓ Review sole trader vs limited company as income grows

FAQs

What does an accountant for plumbers and tradespeople do?
They handle CIS registration and refund claims, VAT domestic reverse charge compliance, VAT registration once you cross the threshold, van and tool expense claims including capital allowances, and general Self Assessment or limited company accounts for trade businesses.

Do I need to register for CIS as a plumber?
If you work as a subcontractor for a contractor in construction, which includes most plumbing and electrical subcontract work, yes — CIS registration means 20% tax is deducted instead of 30%, credited against your final tax bill.

Am I likely to get a CIS refund?
Many subcontractors are. CIS deductions are calculated on your gross invoice amount before business expenses are deducted, so the tax you actually owe once expenses are accounted for is often less than what’s already been withheld.

What is the VAT domestic reverse charge for construction?
A rule that shifts responsibility for accounting for VAT from the subcontractor to the contractor on most construction services, meaning subcontractors often don’t charge VAT on these invoices at all. It’s been in place since March 2021.

When do I need to register for VAT as a tradesperson?
Once your taxable turnover exceeds the current threshold — £90,000 — in any rolling 12-month period, not just the tax year, registration becomes compulsory.

Can I claim my van and tools against tax?
Yes. Day-to-day fuel, small tools, and materials are generally allowable expenses, while larger purchases like a new van or significant equipment upgrade often qualify for the Annual Investment Allowance, allowing the full cost to be claimed in the year of purchase.

Should I use the mileage rate or actual costs for my van?
You can choose either method for vehicle expenses, but you must apply it consistently once chosen. Mileage rate is often simpler for a single vehicle; actual costs can work out better for higher-cost vehicles, but requires more detailed record-keeping.

Should I be a sole trader or set up a limited company?
It depends on your income level, growth plans, and how much admin you’re willing to take on — limited companies can offer tax efficiency and liability protection at higher income levels, while sole trader status keeps things simpler for smaller-scale work.

Do I charge VAT under the domestic reverse charge?
Generally no — on most construction services covered by the charge, the contractor accounts for the VAT instead, and the subcontractor’s invoice should state that the reverse charge applies rather than adding VAT.

How much does an accountant for tradespeople typically cost?
Fees typically range from £180 for straightforward CIS subcontractor Self Assessment up to £500 for more complex trade businesses with multiple contractors or limited company structures, with VAT return support usually charged separately once registered.

Sources

• GOV.UK — Construction Industry Scheme (CIS)
• GOV.UK — VAT domestic reverse charge for building and construction services
• GOV.UK — VAT registration thresholds
• GOV.UK — Annual Investment Allowance

CIS deduction rates, VAT thresholds, reverse charge rules, and capital allowance limits are set by HMRC and subject to periodic review — always confirm current figures on GOV.UK before relying on them.

Final Thoughts

Construction subcontracting is one of the few areas of UK tax where the gap between doing it yourself and getting specialist help shows up directly in your bank balance — through an avoidable 30% deduction rate, a missed capital allowance on a van or tool purchase, or a VAT registration deadline that arrives sooner than expected. Getting CIS, VAT, and equipment relief right protects cash flow that’s rightfully yours.

If you’re unsure whether you’re paying the right CIS rate, missing eligible expenses or capital allowances, approaching the VAT threshold, or simply wondering whether it’s time to consider a limited company, speaking with a specialist trade accountant is the clearest way to find out.

Written by:
Shamayun Chowdhury
Senior Accountant, Major Accountancy
Lecturer in Accounting, Nottingham Trent University
CIMA Qualified, 15+ Years Experience
Last Reviewed: August 2026