How to write an Application for Payment under NEC4, and make it dispute-proof

I've reviewed hundreds of payment applications from M&E subs. Most share the same problem: they state a number but don't prove it. The application says "Mechanical first fix, 65% complete, £184,000" and that's it. No breakdown of that 65%. No reference to the activity schedule. No evidence of what was actually installed.

Then the PM certifies £140,000 instead of £184,000. The subcontractor is furious and the argument begins. But when you ask them to demonstrate how they arrived at their figure, they can't. Not clearly, not with evidence, and not in a way that would survive 10 minutes in front of an adjudicator.

The Payment Act gives you statutory protection on timelines. But it doesn't help if your application is so poorly evidenced that the PM has grounds to certify lower. You want to get paid what you're owed? Every line item needs backing that the other side can't reasonably dispute.

What NEC4 Option A requires in an AFP

Under NEC4 Option A (priced contract with activity schedule), your AFP is based on the Price for Work Done to Date (PWDD). That's the total of prices for each completed activity, plus the price for any completed proportion of grouped activities.

Under Option A, you don't get paid for partially completed activities unless your activity schedule allows it. If your schedule has one line saying "Mechanical first fix, levels 1-8, £280,000" and you've done levels 1 to 4, you're technically not entitled to anything until the whole activity is done.

In practice, most subcontracts allow interim payments based on proportional completion. But check your specific conditions. Many main contractors use bespoke Z-clauses or amended payment provisions that change how PWDD is calculated.

Get the activity schedule right at tender stage. Break mechanical and electrical work into measurable chunks: by floor, by system, by area. Each activity should be clearly demonstrable as complete or not. "LTHW pipework level 3" is assessable. "Mechanical installation phase 1" is not.

The evidence problem

Here's what actually happens on most M&E subcontracts. The QS sits down on the 20th of the month. They look at progress reports, make percentage estimates, and submit the application. The percentages come from experience and gut feel. Sometimes they walk the site. Sometimes they don't.

The PM, or more likely the main contractor's QS, does their own assessment. They walk the site, form a different view, and certify lower. Now you've got two opinions and no objective evidence to settle it.

The evidence problem has three parts:

1. No link between the application and the activity schedule. Your application should reference specific activity schedule items. It should state exactly which ones are claimed as complete. Most applications don't do this.
2. No contemporaneous records of completion. If you say level 3 LTHW pipework is 100% complete, you should have dated photos, test certificates, and sign-off records proving it. Most subs have some of this scattered across phones and email threads. None of it is assembled to support the application.
3. No clear separation between contract work and CE work. CEs often get lumped in without identification. The PM can't tell what's contract scope and what's a CE. That gives them a reason to query the whole application.

How to structure your AFP properly

A dispute-proof NEC4 payment application should contain the following:

A cover sheet stating the assessment date, application number, total amount applied for, and cumulative amount previously certified. This seems obvious. A surprising number of applications don't clearly state what period they cover.

An activity schedule summary listing every activity. Show the contracted price, percentage claimed complete, and resulting amount. The total is your PWDD. Make this a table, not a narrative. The PM needs to check each line independently.

An evidence pack for each completed activity. For activities at 100%, include dated photos of installed work, test or commissioning certificates, and inspection sign-off records. For activities at a percentage, include a clear description of work done and remaining, with photos.

A separate CE schedule showing all CEs in the application. Each CE should reference its notification number, the PM's instruction or assessment, the agreed amount, and how it's included in the PWDD. More on this below.

A reconciliation showing: previous certified amount, plus newly completed activities, plus CE amounts, minus corrections, equals total applied for.

CE items: how to include them correctly

This is where most M&E applications fall apart. CEs under NEC4 change the activity schedule. When a CE is implemented, meaning the PM has accepted or assessed the quotation, the schedule updates. The CE amount becomes part of your prices.

Show CEs in two categories in your application:

• Implemented CEs: These have been through the full process. Quotation accepted, or PM has assessed it. Your activity schedule prices are updated. Include the work like any other completed or partially completed activity.
• Notified but not yet implemented CEs: Trickier. You've notified the CE and maybe submitted a quotation, but the PM hasn't accepted it. Under strict NEC4 terms, these don't change your prices until implemented. But if the PM is failing to respond in time, you may have a deemed acceptance argument.

Don't bury CE amounts inside your regular activity percentages. If you claim level 3 LTHW at 100% and part of that was a variation, the PM can't verify your figure without unpicking everything. Keep contract work and CE work visibly separate.

What to do when your AFP is partially certified

When the PM certifies less than you applied for, you'll get a payment certificate showing the certified amount. You have the right to refer the dispute to adjudication if you believe the figure is wrong.

Before you go that route, do this:

1. Request a breakdown of the certification. Ask the PM to explain, line by line, which activities they've valued differently and why. Under NEC4, the PM should justify their assessment.
2. Compare their assessment to your evidence. If your application is properly structured, go through each disputed activity. Test whether your evidence supports your figure or theirs.
3. Work out if the dispute is about completion or valuation. These are different problems. The PM says your pipework isn't complete and you have photos showing it is? That's an evidence dispute you can win. The PM disagrees with your percentage and you don't have records? That's harder.
4. Respond formally in writing. Don't just argue about it in a meeting. Write to the PM identifying each disputed line item. State your assessed value. Attach the evidence.

The subs who get paid properly aren't better at the physical work. They're better at proving what they've done. Every hour you spend building a proper evidence trail saves you days of argument and thousands in under-certification later.