Recurring legal review rather than a single preparation fee. Set aside an allowance for periodic checks and for the possibility that a material change requires an amended filing. The internal cost of maintaining the duty record is small; the cost of reconstructing two years of scope changes under time pressure is not.
Ask for a retainer shaped around review
A scope that covers occasional questions as they arise fits a moving project better than one priced for a single filing. Ask what an amendment would involve and what triggers one, so the business can budget for it rather than treating it as an unexpected event. Confirm official charges at the time of any step, since they change independently of the project.
Hypothetical example: a project supporting cold-chain telemetry systems is extended twice and moved to two additional sites within a year, and each change is discussed with counsel only after it takes effect. A first review would price the alternative: a small recurring allowance for scheduled checks, plus a contingency for one amendment. Set against the cost of reconstructing a scope history under pressure, the recurring arrangement is usually cheaper and always calmer.
Ask what specifically would trigger an amendment, so the contingency has a definition rather than a number attached to a worry.