Construction Progress and Payment Calculator

What does this tool calculate?

On a unit price contract two questions come up at the end of every period: how far has the work progressed, and how much is due this period? The tool takes each work item's contract quantity, unit price, cumulative quantity from previous periods and quantity done this period. It gives the amounts item by item, the overall physical progress and the amount payable after tax and deductions.

Order of calculation

• Cumulative quantity = previous cumulative quantity + quantity this period
• Cumulative amount = cumulative quantity × unit price
• Amount this period = cumulative amount − previous amount
• Physical progress = cumulative value of work done / contract sum
• Tax = amount this period × tax rate
• Deduction = amount this period × deduction rate, or a fixed amount
• Payable = amount this period + tax − deductions

Why is progress weighted by value?

A plain average of item percentages misleads. If a small item is finished and a large one has not started, the average shows 50 percent although very little of the job is done. So each item carries a weight equal to its contract amount.

Example

Take a three item job with a contract sum of 2,550,000. If previous payments total 580,000 and the cumulative work done at the end of this period is 1,270,000, the value this period is 690,000 and progress is 49.8 percent. A 20 percent tax adds 138,000. Two deductions of 5 and 10 percent plus a fixed 1,500 take off 105,000. The amount payable is 723,000. The rates here are only an example.

Deductions and tax

The tool assumes no rate. The rate and base of retention, advance recovery, withholding tax, stamp duty and similar items depend on the contract, the type of work and the applicable rules. You add each deduction by name and enter its rate or amount. Percentage deductions are calculated on the period amount before tax. Enter a deduction with a different base as a fixed amount.

Limits

Price adjustment, new unit rates, variations and delay damages are outside the scope of this tool. The result is a preliminary calculation and does not replace a formal payment certificate. For firm amounts refer to your contract and your accountant.