Why Subcontractor Payments in UK Construction Are Broken and What the Fix Looks Like

UK construction has a payment crisis. Late invoices, CIS compliance failures, and tools built for accountants instead of site workers are costing subcontractors billions every year. This post covers why the system fails, who it fails hardest, and what a real fix looks like.

Construction Payments Are Broken by Design

Construction is the backbone of the UK economy. It employs millions, builds the hospitals, schools, roads, and homes the country depends on. And it pays its workers late, incorrectly, and without the tools to do anything about it.

This is not an accident. The payment chain in construction is structurally adversarial. Main contractors hold cash as long as possible. Subcontractors absorb the risk. HMRC adds a mandatory deduction layer on top through the Construction Industry Scheme. The result is a system where the people doing the actual work are the last to get paid and the most exposed when things go wrong.

Construction had the highest insolvencies of any UK sector in 2024, with 4,032 company failures (Hill Dickinson, 2025). That is not a run of bad luck. That is a structural problem with structural causes.

The Workforce Gap: 2.5 Million Workers, Zero Tools

There are more than 2.5 million construction workers in the UK (UK Gov). They are electricians, groundworkers, plasterers, steel fixers, roofers. Most work as self-employed subcontractors or through small companies. Many move between sites, GCs, and projects week to week.

Not one mainstream fintech product has been built for them. Not one.

The invoicing tools that exist assume a fixed client base, a desktop computer, and time to sit down and think about accounting. None of those assumptions hold on a construction site. A subbie finishes a pour at 4pm, needs to invoice before the GC's payment run closes, and has a phone with cracked glass and dirty hands.

The gap is not a niche. 2.5 million workers is a market. It has simply been ignored because it looks hard to serve. That is the opportunity.

The Compliance Trap: Every Invoice Is a CIS Event

The Construction Industry Scheme is the UK government's mechanism for collecting tax from subcontractors at source. Every payment a contractor makes to a subcontractor under CIS is a compliance event. The contractor must verify the subcontractor's status with HMRC, apply the correct deduction rate, pay the net amount, and file a monthly return by the 19th of each month.

The deduction rates are not optional. Standard rate is 20%. Unverified subcontractors face 30%. Gross payment status subcontractors receive 0% deduction. Getting this wrong is not a minor error. Contractors remain liable for under-deducted CIS tax for up to six years. A missed monthly return triggers a minimum £100 penalty per month.

Most SME main contractors manage this via spreadsheets or by relying on an accountant who is not on site. The subcontractor has no visibility into whether the deduction is correct. There is no audit trail created at point of invoice. Both sides are flying partly blind.

This is not a tax technicality. It is a cash flow and legal liability issue that touches every single subcontract payment in the UK.

The Tool Mismatch: Built for Desks, Not Sites

Xero is a good product. So is Sage. They were built for businesses with offices, finance teams, and predictable monthly billing cycles. They were not built for a sole trader who completes a three-day job on a residential development and needs to raise a CIS-compliant invoice before driving to the next site.

The friction is real. Log in, create a client, set up a project, remember the correct CIS deduction rate, generate the invoice, download a PDF, email it. That sequence assumes time, connectivity, and familiarity with accounting software. Most subbies do not have all three simultaneously. Petl Pay internal research estimates up to 16 hours per month lost to manual subcontractor invoice and payment management.

The tool mismatch is not about capability. Subcontractors are skilled, organised people. They run complex jobs under pressure. The tools have simply never met them where they are.

The Payment Lag: Billions Lost, Nothing Changes

77% of UK subcontract projects experience late payment (Aston University / Journal of Legal Affairs, 2022). Late payment costs UK businesses £10.7bn per year (UK Government DBT, 2025). UK construction businesses are owed more than £30bn in unpaid invoices (Sharpe Pritchard, 2024). Sixteen UK businesses fail every day because of late payment (DBT, 2025).

These are not abstract statistics. They are the reason subcontractors cannot make payroll, cannot invest in equipment, and cannot take on more work. The payment lag compounds every other problem in the system.

Without a structured invoice created at the point of work, a subcontractor has no paper trail and no leverage when chasing payment. The GC can dispute the amount, claim the invoice never arrived, or simply deprioritise the debt. A timestamped, CIS-compliant invoice sent at point of completion changes that dynamic entirely.

The Fix: Invoicing Where the Work Happens

01. WhatsApp as the Interface (Coming Soon)

The interface that matters most to UK subbies is already on their phone. Petl Pay is building a WhatsApp-native invoicing flow where a subcontractor messages Petl, describes the work completed, and the AI generates a fully CIS-compliant invoice and routes it directly to the general contractor. No app download. No login. No learning curve.

This is coming soon. It is not live today. But the architecture is being built around one principle: the invoice must go where the work happens, not where an accountant sits.

02. CIS Compliance Built In, Not Bolted On

Every invoice generated through Petl Pay handles CIS as a default, not an afterthought. The platform auto-calculates the correct deduction rate, verifies subcontractor HMRC status, and generates the documentation both sides need for monthly returns and future audits. The compliance burden shrinks for GCs. The transparency increases for subbies. Both sides get an audit trail created at the moment of invoicing, not reconstructed from spreadsheets weeks later.

03. A Network That Scales Itself

Construction works in networks. A groundworks sub brings in the same GC on three different jobs. An electrician recommends a plasterer. One project connects multiple businesses. Petl Pay is designed to scale through those existing relationships. When a subcontractor onboards, they pull their GC into the network. One project generates multiple new users. The growth is structural, not dependent on paid acquisition alone.

04. Construction Is the Wedge, Not the Ceiling

The same infrastructure that handles CIS-compliant subcontractor invoicing already powers agencies, freelancers, and cross-border teams on Petl Pay today. Construction is the wedge because the pain is highest and the tools are worst. But the platform is built for every workforce that bills irregularly, moves between engagements, and needs compliance handled without friction.

Frequently Asked Questions

What is CIS and why does it affect subcontractor payments?

The Construction Industry Scheme (CIS) is a UK government tax scheme requiring contractors to deduct tax from subcontractor payments at source and remit it to HMRC. Deduction rates are 20% for registered subcontractors, 30% for unverified ones, and 0% for those with gross payment status. Every subcontract payment is a CIS event, triggering a compliance obligation for the paying contractor.

Why do UK subcontractors get paid late?

Late payment in UK construction stems from structural cash flow pressure on main contractors, poor invoicing discipline down the supply chain, and the absence of enforceable audit trails at point of work. 77% of UK subcontract projects experience late payment (Aston University / Journal of Legal Affairs, 2022). Without a timestamped, compliant invoice sent at completion, subcontractors have limited recourse when chasing overdue payments.

What is the penalty for getting CIS wrong as a contractor?

Missing a monthly CIS return by the 19th triggers a minimum £100 penalty per month. Contractors who under-deduct CIS tax remain liable to HMRC for the shortfall for up to six years. For SME main contractors managing multiple subcontractors, manual CIS processes carry material legal and financial risk.

What tools exist for subcontractor invoicing on construction sites?

Most subbies use generic accounting software such as Xero or Sage, manual Word or Excel invoices, or nothing at all. None are designed for CIS compliance, mobile-first use, or point-of-work invoicing. The gap between what subbies need and what exists is the problem Petl Pay is built to close.

How does Petl Pay handle CIS compliance?

Petl Pay builds CIS compliance into the invoicing flow by default. The platform auto-calculates deduction rates based on verified HMRC subcontractor status, generates CIS-compliant invoices, and produces the documentation contractors need for monthly returns and long-term audit records. Compliance is not a separate step that gets skipped under time pressure. It is built into every transaction from the start.

Construction payment has been broken for decades. The tools to fix it exist today. If you are a subcontractor, a general contractor, or a business owner tired of managing invoices and CIS manually, Petl Pay is built for the way construction actually works. Visit petlpay.com to get early access.