Separate an estimate from a readiness claim
A delivery estimate can describe what the supplier expects after work begins. It does not establish that the required access, current data, buyer decisions, or third-party work are available today. List those prerequisites in their own record instead of burying them in a project-plan assumption.
For each item, name the accountable owner, the evidence that makes it ready, the date it is needed, the fallback or decision if it is unavailable, and the stated schedule consequence. “Buyer supplies data” is not yet a usable entry; the buyer and supplier still need to agree which data, in what condition, where it is authorised to appear, and who confirms readiness.
Use a prerequisite register before a start commitment
The accompanying implementation-prerequisite register keeps five common categories visible: access or identity, authoritative data, scope or policy decision, external service, and buyer-side resource. Add or remove categories for the actual work. Do not mark a critical item complete because it was discussed; retain the agreed readiness evidence.
If a critical prerequisite has no owner, verification method, fallback, or stated consequence, the buyer's safe record outcome is “clarify before start.” That does not accuse either party of causing a delay. It prevents an unowned assumption from being mistaken for a committed date.
Keep the boundary commercial, not legal
This is not a contract template or advice about who bears delay risk. It is a comparison aid for the buyer's operating decision. The agreement, proposal, and qualified adviser govern their own terms. Once the work is underway, use a separate change record for a request that alters the agreed baseline.
For the price-and-scope comparison that happens before readiness, see Normalize Competing Custom Software Quotes. For the later evidence needed before final payment, see What Should Final-Payment Acceptance Prove?.
Does every project need the same prerequisite list?
No. The list should match the actual proposed work. The reusable rule is that a critical prerequisite needs an owner, readiness evidence, next decision, and stated schedule consequence.
Does a missing prerequisite automatically mean a supplier is at fault?
No. The record does not allocate fault. It makes an assumption visible so the authorised people can clarify, defer, change scope, or choose another path.