Progress Payment Cashflow Calculator NZ 2026
Reviewed 5 August 2026.
Project work fails on cash far more often than it fails on price. A job can be quoted well, run to programme and turn a genuine profit, and still put a business under, because the money goes out steadily from the first week and comes back in one lump at the end. The gap between those two is not an accounting abstraction, it is an overdraft or a credit card or an invoice from a supplier you cannot pay yet, and its size is entirely determined by the payment structure in the contract rather than by anything about the work itself. A deposit is worth more than a progress claim of the same amount because it arrives before you have spent anything. A progress claim is worth more than a longer payment term is worth taking away. This calculator runs your project day by day under three structures, and reports the deepest point your cash reaches, how long you stay down there, and what funding that gap costs, so that the payment terms can be argued about with a number attached.
The job
Your staged structure against payment on completion
Three payment structures on the same job
Same work, same costs, same terms. Only the timing of the money changes. Your own structure is highlighted.
| Structure | Peak funding | Days in deficit | Funding cost | Cash positive from |
|---|
Why the deposit does the heavy lifting
Every payment reduces the peak, but not by the same amount, and the difference is about timing rather than size. Your cash position falls fastest at the start, when costs have begun and nothing has come in, so money arriving early lands exactly where the hole is deepest. A deposit paid before work starts offsets those first weeks almost dollar for dollar. A progress claim raised at the halfway point arrives after the position has already been dug, and pulls the later part of the curve up without touching the early part at all. That is why negotiating a deposit up from ten percent to twenty is usually worth more than adding another progress claim, and why a job with no deposit is a job you are financing regardless of how many claims follow.
The peak matters more than the profit
The number that decides whether you can take a job is not the margin, it is the deepest point of the cash curve, because that is what has to exist in an account before you start. When the peak exceeds the profit, and on payment-on-completion terms it very often does, the job is consuming more capital than it generates until the day it settles. Run two such jobs at once and the requirement doubles while the profit only doubles at the end. This is the mechanism behind the oldest pattern in trade businesses: growth in the order book producing a cash crisis rather than a windfall, with the crisis arriving precisely when things are going well.
Worked example
A $60,000.00 job runs 12 weeks with costs of 60% of the value, which is $36,000.00, leaving $24,000.00 of profit. Costs run at $3,000.00 a week. A 20% deposit of $12,000.00 is claimed at the start and three progress claims plus the final claim of $12,000.00 each follow, all paid 30 days after they are issued, with the last money arriving on day 114.
On that structure the cash position bottoms out at $12,428.57 and stays negative for 75 days, costing $113.71 to fund at 12%. Paid on completion instead, the peak is $36,000.00 across 113 days, costing $846.25. Staging the payments therefore reduces the cash you must find by $23,571.43, and the interest saved is $732.54. The interest is the small number and the peak is the large one, which is the point: this is a capital problem, not an interest problem.
How this is calculated
The project is simulated a day at a time. Total cost is the project value multiplied by your cost percentage, spread evenly across the days of the project. The deposit is claimed on day zero and every other claim is spread evenly across the project length, with the final claim on the completion day, and each is received the number of days later that you set as your payment terms. The running balance is costs out and receipts in, and the peak funding requirement is the deepest that balance reaches. Days in deficit counts every day the balance is below zero. Funding cost applies your annual rate divided by 365 to each day's deficit, which is how an overdraft charges. The three structures compared are identical except in when the money is claimed.
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How to work out the cash a project ties up
- Enter the project value and length. What you are charging and how many weeks the work runs for.
- Enter your costs as a share of the value. Materials, labour and subcontractors, which you have to fund as the work happens.
- Set the deposit and the number of progress claims. A deposit lands at the start; progress claims are spread evenly across the job with the balance on completion.
- Enter your payment terms. The days between issuing a claim and the money arriving. This is the assumption that moves the answer most.
- Read the peak funding. The deepest your cash position goes. That is the money you need available before you start, not the profit at the end.