7 Critical Mistakes That Destroy Construction Cashflow — And How to Fix Them

22 May 2025

Accounting & Compliance, Building & Construction, Building a Business, Cloud Accounting, Reducing Tax

Cashflow is the lifeblood of any business.

But in the construction industry, it’s absolutely critical.

With long project timelines, upfront costs, retention and main contractor discount clauses, and late-paying clients, construction companies face a uniquely volatile cashflow environment.

Even profitable businesses can run into serious trouble if they don’t manage their cash well.

In this blog, we’ll explore seven common cashflow mistakes made by construction firms in the UK, and how you can take simple but effective steps to avoid them.

Poorly Structured Contracts

The Mistake:

One of the biggest contributors to cash flow stress is weak or poorly structured contracts.

Without clear payment terms and protections in place, companies are left exposed to late payments, withheld retentions, or disputes over what work has been done.

In many cases, builders rely on verbal agreements or generic templates that don’t reflect the real financial needs of the job.

This can result in work being completed before a single invoice is raised, and in some cases, not being paid at all.

The Fix:

Make sure every contract is written clearly and includes:

Milestone-based payment terms
Penalties for late payments
Clear retention clauses
Payment timelines that align with your supplier and subcontractor payments

Work with a solicitor who understands the construction sector to protect your position.

For smaller projects, templates from industry bodies like JCT can provide a solid starting point.

Failing to Invoice Promptly

The Mistake:

It sounds obvious, but many construction firms delay invoicing.

Whether it’s due to busy site work, admin overload, or waiting for the “right time”, this delay creates cashflow gaps that can quickly spiral.

In some cases, invoices are raised late, sent with errors, or not chased up, all of which delay payment.

The Fix:

Set up a clear invoicing process that is tied to project milestones or scheduled dates.

Use software like Xero with job management integrations (like Tradify, Buildertrend or SimPRO) to automate this.

Train your admin staff or appoint a dedicated accounts person to stay on top of invoicing and follow-ups.

Accepting Work Without Credit Checking the Client

The Mistake:

It’s tempting to say “yes” to any big project that comes your way, especially when work is slow.

But not all clients are good clients, and taking on a job with someone who can’t or won’t pay is a quick route to disaster.

Many contractors get burned by assuming a large developer or contractor is financially stable without checking their actual payment history or creditworthiness.

The Fix:

Before you sign the contract, run a credit check on the client using tools like Creditsafe, Experian Business, or Company Check.

Look for signs of:

Late payment trends
County Court Judgments (CCJs)
Negative press or contractor reviews
Recent changes in directorships or ownership

This small upfront step could save you thousands later.

Not Tracking Work in Progress (WIP) Accurately

The Mistake:

A huge issue in construction accounting is the lack of visibility around work in progress (WIP).

If you’re not tracking how much of a project is actually completed and what’s been billed against it, you’re likely underbilling, and overstating profit.

WIP mismanagement can lead to jobs appearing profitable when they’re not, or invoices being delayed because you haven’t kept track of milestones.

The Fix:

Track WIP weekly, not just at month-end.

Use job management tools or a good old spreadsheet to record:

Stage of completion
Costs incurred
Materials delivered
Labour time logged

This helps you spot underperformance, over-runs, and opportunities to bill more quickly.

Ignoring Retentions and Late Payments

The Mistake:

Retentions are standard in construction, but they’re also one of the most commonly overlooked cashflow drains.

Many businesses forget to chase retentions when they become due, or don’t account for the delay in their cashflow forecast.

Combined with late-paying clients, it’s easy to see how a job you finished six months ago can still be affecting your bank balance today.

The Fix:

Maintain a Retention Tracker listing:

Job name
Amount retained
Due date for release
Conditions for release

Use this to prompt timely follow-ups and ensure your team is collecting money owed.

Build retention payment assumptions into your cash flow forecast, don’t assume it will be paid immediately.

Also, implement a strict payment follow-up process.

Don’t be afraid to chase clients regularly and escalate if needed.

Mixing Business and Personal Finances

The Mistake:

Many directors of small construction firms take dividends or draw money from the business without planning.

This can leave the company without enough cash to meet tax bills, pay suppliers, or deal with slow-paying customers.

It also creates confusion when trying to understand the true profitability and cash health of the business.

The Fix:

Establish a regular, tax-efficient director’s remuneration plan.

Typically, this means:

A small monthly salary up to the National Insurance threshold
Quarterly or annual dividends declared based on actual retained profits
Interest a charges on any loans made to the company personally.
Involving the family in profit sharing/remuneration.
Low/No tax benefits

Never treat the business account like a personal piggy bank.

Keep funds in the business to protect against lean months or unexpected costs.

Not Ring-Fencing VAT and CIS Liabilities

The Mistake:

It’s all too common for businesses to spend VAT collected from clients, only to find they can’t afford to pay it to HMRC at quarter-end.

Similarly, companies acting as contractors under the Construction Industry Scheme (CIS) may overlook tax deductions and be caught short.

This leads to tax arrears, penalties, and a ticking time bomb under your cashflow.

The Fix:

Set up a separate bank account for VAT and CIS deductions.

Every time you receive a payment that includes VAT, transfer the VAT portion immediately into this account.

The same applies to CIS deductions made from subcontractors or taken from your own invoices.

Treat this money as off-limits.

Cashflow Isn’t Just an Admin Job – It’s a Survival Skill

Running a construction business is tough.

You’re juggling multiple projects, managing teams, dealing with client demands, and the last thing you need is a cashflow crisis to derail everything.

But with the right habits and systems in place, you can build a business that’s financially strong, resilient, and ready to grow.