For owner-managed construction companies · £200k–£5m

Accountants for construction companies

CIS deductions, the domestic reverse charge, retentions and contract work in progress — the four things that make construction books different, handled monthly by a Chartered Management Accountant. Fixed fee from £199 + VAT.

Book a 30-minute initial review →
Regulated byCIMA
Member in Practice
Companies HouseNo. 16943160
Insight Professional Partners Ltd
CoverProfessional
Indemnity Insured
Delivered onYour existing
Xero
Why construction books go wrong

Four things a general bookkeeper usually gets wrong

Construction is the sector where ordinary bookkeeping breaks down fastest. Not because the transactions are complicated, but because four specific rules change how they should be recorded — and someone without construction experience will code them the obvious way, which is the wrong way.

1. CIS deductions recorded as a cost

Deductions suffered on your own sales are not an expense. They're tax paid in advance and belong on the balance sheet, to be set against your PAYE liability or reclaimed. Recording them as a cost understates turnover and understates profit — so the business looks less profitable and less valuable than it is.

Deductions you make from subcontractors run the other way: a liability until paid over. Getting these two the wrong way round is the most common construction error we see, and it's usually been running for years.

2. The domestic reverse charge applied to the wrong supplies

Where both parties are VAT registered, the work is within CIS and the customer isn't an end user, the subcontractor charges no VAT — the customer accounts for it on their own return instead.

Two errors dominate. Treating an end user as a contractor, which wrongly removes VAT from an invoice that should carry it. And forgetting that materials supplied with the labour fall within the charge too, so the invoice gets split when it shouldn't be. Both distort the VAT return, and both are the sort of thing an inspection finds quickly.

3. Retentions left out entirely

Retention held by a customer is still your income and remains a debtor until it's released or written off. Leave it out and revenue and profit are understated — and, more practically, money sits uncollected because nobody is tracking what's due back and when. Retention you hold from subcontractors is a creditor and needs the same treatment in reverse.

4. Contracts spanning the month end

A job that starts in one period and finishes in another needs the income and cost matched to the same period. Applications for payment, work done but not yet certified, and materials on site all need handling deliberately. Otherwise a good month and a bad month simply reflect when invoices happened to be raised.

The cumulative effect. Get all four wrong and your monthly numbers are not slightly off — they're describing a different business. That matters most at the two moments it's hardest to fix: when a lender asks for management accounts, and when you come to sell.

What we do each month

What we don't do, plainly. Corporation Tax returns and personal Self Assessment sit outside CIMA's scope of practice and are referred to a UK Chartered Accountancy firm we work with. If you want one firm doing everything including tax, we're not it — and it's better you know now.

Who this suits

Owner-managed construction companies turning over roughly £200k to £5m — groundworks, fit-out, M&E, civils subcontractors, small main contractors and specialist trades. Typically businesses where the books are done by the owner, a spouse, or a part-time bookkeeper without construction experience.

Work is delivered on your existing Xero, so location isn't a constraint, though we're based in Cambridgeshire and work across the surrounding counties in person where that helps.

What it costs

Bookkeeping is £199 + VAT a month, fixed. Management accounts and Virtual FD support are quoted after a free initial review, because what they cost depends on the size and state of the business. See what UK bookkeeping typically costs for context, or work out what your current arrangement costs.

Think the CIS treatment might be wrong?

The free Bookkeeping Health Check scores your books out of 100 and shows you what's wrong. No login, nothing uploaded, no obligation.

Run the free Health Check → Or book a 30-minute initial review