Fractional CFO for Construction: A UK Contractor's Guide

TL;DR

A fractional CFO for construction businesses is a senior finance leader who works part-time to protect project margins, control work in progress and retentions, forecast cash and keep Construction Industry Scheme (CIS) compliance tight. With construction recording more insolvencies than any other UK sector, contractors turning over £5m to £100m increasingly use one to get board-level finance without a full-time CFO salary.

Last updated: 2 November 2026

Demand for a fractional CFO for construction firms is rising for a simple reason: the sector is where financial pressure shows first. According to the Insolvency Service, 3,873 construction companies entered insolvency in England and Wales in the 12 months to September 2026 — 17% of cases where an industry was recorded, the highest of any sector.

The headline hides wide variation. BCIS reports that insolvencies among road and railway construction firms rose 24.4% over the same period, demolition and site preparation rose 15.6%, and specialist contractors accounted for 168 of September's 285 construction insolvencies. Many of those businesses were busy, with full order books, when they failed.

Construction firms rarely fail for lack of work. They fail because cash, margin and risk were not visible early enough. This guide explains what a fractional CFO does in a construction business, the warning signs that you need one, and how an engagement works.

Why construction finance is different

Construction finance has features that general finance teams often underestimate:

• Project accounting — profit is earned contract by contract, and an overall margin can hide loss-making jobs until it is too late.
• Work in progress and valuations — applications for payment, certified values and costs to complete need to be reconciled every month.
• Retentions — typically 3% to 5% of contract value held back for months or years, tying up working capital.
• Variations and claims — agreed changes that are not priced and recovered quickly erode margin.
• Supply chain risk — a failing main contractor or key subcontractor can leave unpaid applications and disrupted programmes.
• CIS compliance — deductions, verification and monthly returns that directly affect cash flow.

A generalist accountant can produce accurate year-end accounts and still miss the problems that matter most to a contractor's survival.

What does a fractional CFO for construction do?

A good construction CFO starts with project-level visibility. They introduce monthly cost-value reconciliations for every live contract, so the board sees forecast margin and costs to complete rather than just invoiced revenue. Loss-making jobs are spotted in month two, not at final account.

They build a rolling 13-week cash flow forecast that reflects application dates, payment terms, retentions, CIS deductions and supplier runs. They tighten bid governance so tenders are priced on realistic overheads and risk, and they set rules on payment terms, bonds and parent company guarantees before contracts are signed.

They also manage the relationships that keep a contractor funded: banks, surety providers, credit insurers and, for larger firms, investors. Accurate, timely management accounts make every one of those conversations easier. Where the finance team needs better systems, they lead the move to construction-ready software and reporting.

CIS changes raise the stakes in 2026

The Construction Industry Scheme changed on 6 April 2026. Under new fraud measures, if a business makes or receives a payment that it knew or should have known was connected to fraud, HMRC can immediately remove Gross Payment Status, assess the business for the tax lost and charge a 30% penalty that can apply to the business or its officers. Businesses that lose Gross Payment Status this way cannot reapply for five years.

Contractors must also now file nil returns in months when they have paid no subcontractors, unless they notify HMRC in advance. Losing Gross Payment Status would mean 20% deductions from payments received — a severe cash flow hit. A fractional CFO makes sure subcontractor verification, supply chain due diligence and monthly returns are robust enough to stand up to scrutiny.

Signs your construction business needs a fractional CFO

• Turnover is growing but cash in the bank is not.
• Project margins at final account regularly come in below tender.
• You do not have a reliable 13-week cash flow forecast.
• Retentions owed to you are not tracked or chased systematically.
• Your bank, surety or credit insurer is asking for more information than you can easily provide.
• You are tendering for larger contracts, frameworks or public-sector work that requires stronger financial governance.
• The managing director is spending evenings on finance instead of winning and delivering work.

Picture a £30m regional building contractor with a full order book and a finance team of four. Cash is tight despite record turnover. A fractional CFO from our bench introduces monthly cost-value reconciliations, finds two contracts heading for losses and renegotiates variations on both. A retention recovery exercise releases significant cash owed on completed jobs, and a 13-week forecast gives the bank the confidence to renew facilities.

How a fractional CFO engagement works

Most engagements start with a short review of project margins, cash, systems and controls. The CFO then agrees priorities with the managing director and typically works one to three days a week, flexing up for year-end, refinancing or a major bid. The cost is a fraction of a full-time hire — our guide to fractional versus full-time CFO costs sets out the numbers.

The right fractional CFO for construction businesses will have worked with contractors before and understands valuations, retentions and CIS without needing a briefing. Our fractional CFO services and part-time finance directors are drawn from a bench that includes leaders with construction and property experience. If your systems and data also need attention, see our guide to a fractional IT director for construction.

Frequently asked questions

Ready to protect your margins and cash?

Leadership Services gives UK construction businesses access to a bench of 500+ senior directors, including CFOs and finance directors who understand project accounting, retentions and CIS. Engagements start from £1,795 per month, begin within one week and have no long-term tie-ins — get in touch and we will respond the same working day.