Service Contracts & Milestone Billing

The milestone-definition test

“Design 60% complete” is not a milestone. It is a disagreement with a payment attached. The consultant believes it is 60% complete. Your project manager believes it is 40% complete. Both are sincere, neither can be proved wrong, and the invoice is already in the system.

The test is verifiability, applied at DEFINITION time: could two reasonable people, looking at the same evidence, disagree about whether this milestone has been achieved? If yes, it is not a milestone — it is a future argument that you have agreed to pay for.

“Stage 2 design package issued for review, comprising drawings X through Y to revision C” passes the test. Something either was issued or it was not. There is a transmittal. The disagreement, if there is one, is about quality — which is a different conversation, and one that a defined milestone at least allows you to have separately from the payment.

And this is the entire discipline, because it cannot be recovered afterwards. A vague milestone written into a contract in March will be argued about in September, and the argument will be resolved by whoever has more leverage — which, at that point in a professional services engagement, is very rarely you.

What replaces the goods-received note

• Certification is the receipt leg, and the certifier is doing a gate’s job on judgement. In a three-way match on goods, the GRN says what physically arrived. On services, there is nothing to count — so the engineer or project manager who certifies the milestone IS the receipt document. Which means certifier discipline matters exactly as much as gate discipline does, and it is harder: the gate counts, and the certifier judges. Name the certification authority in the contract, and make certification an act with evidence behind it rather than a signature at the end of a month.

• Front-loaded value curves transfer risk to you, quietly and at the start. A milestone schedule that pays 40% at mobilisation and 15% at completion is not a payment schedule. It is a risk transfer, and it is one you agreed to. Value should track effort and deliverable weight — so that at any point in the engagement, the money you have paid is roughly the value you have received. Check the curve at contract setup, because by the time you notice you are 70% paid and 40% delivered, the leverage has already moved.

• Retention and defects obligations apply to services too, and people forget. A design consultant’s errors surface during construction, long after their final invoice. Retention on services — typically in the same 5–10% band that our snag-list page describes for construction — and a defined defects obligation are what keep a party engaged after their fee has been earned. Without them, the incentive to answer the phone about a drawing they issued eighteen months ago is entirely goodwill.

• And the scope-versus-PO question is the same one purchase orders raise. Supervision, insurances, deliverables, liabilities, IP — these belong in a CONTRACT, not on a purchase order. A PO is a commitment to buy a thing at a price. It is not an instrument capable of carrying a professional indemnity requirement, and a services engagement run on a PO with a two-line scope is an engagement that has no answer to the question of what happens when it goes wrong.

• Recurring service agreements need SLAs, not milestones. A maintenance contract has no completion. Its unit of performance is a response time and a fix time — and those need measuring, reporting and enforcing, in the same way a milestone needs certifying. Milestones govern projects. SLAs govern the things that never end.

Where service procurement leaks

The milestone was vague, so it was argued about, so it was paid — because the alternative was a dispute with the consultant whose drawings you still need.

The value curve was front-loaded, so 70% of the fee is gone and 40% of the work is done, and the leverage moved months ago without anyone noticing it happening.

And there was no retention, so the design errors that surface during construction are somebody else’s problem to raise and nobody’s problem to fix — because the party who caused them has been paid, and their file is closed.

How Zepth runs service contracts

Service contracts and POs carrying milestone schedules with named certification authority — and the value curve visible at setup, when a front-loaded one can still be renegotiated rather than merely regretted.

Certification workflows with evidence, so a certificate is an act rather than a signature. Invoices matched against certificates, which is the services leg of the three-way match. Retention tracked to release. And, for recurring agreements, SLAs measured rather than described.