How do I prove I delivered work to a client on time?
Prove it with the record's own times: the steps saved as they ran, each fixed in its receipt; the handover created from the finished job; and your delivery message naming the handover and the deadline it meets. Sent before the deadline, that chain settles the on-time question without a screenshot argument.
On-time disputes are pure timestamp contests, and they are usually fought with the weakest timestamps available: a file's modified date, a sent-folder entry, a memory. Each can be doubted, and the doubt is the dispute. The recorded chain replaces all three with times created by the work itself.
Each step's saved result is committed in its receipt at the moment it was saved (AER-1, IETF Internet-draft-zambo-aer1-21), so the work's completion time is a property of the record, not of your filing. The handover built from those steps carries its own creation time. Your delivery message then only has to prove one small thing, that the link was sent, which any mail system shows; the record proves the rest.
Two habits complete the position. Build the handover when the work finishes, not when the client asks, so its time precedes the deadline naturally. And where a deadline is contractual, name it in the delivery message beside the link ("delivered per the [date] deadline; the record is here"), so the claim and the evidence travel together into whatever thread the future opens.
Checklist: the on-time delivery chain
1. Steps recorded as the work runs (save times in receipts). 2. Handover built at completion, before the deadline where the schedule allows. 3. Delivery message: names the job, the deadline, and the handover link, sent before the deadline. 4. Client decision recorded on the handover with its date. 5. Job folder: delivery message, handover link, invoice, contract deadline page. Test: a stranger with the folder can state the deadline and the delivery time, from the record, without asking you.
Worked example
The chain's public shape: https://zambo.dev/handover/45434a17-4afc-486a-9646-e689bcee4297 shows a job whose steps and client decision sit on one timestamped record. In a deadline argument this object replaces the whole screenshot folder, because its times were fixed while the work happened.
Frequently asked questions
The work was finished on time but I sent it late. What does the record show?
Both times, honestly: step completion and delivery are separate events on the record. That honesty can still help (the delay was transmission, not production), but the habit to fix is delivering the handover at completion.
The client claims they never received the delivery message. Then what?
The record's times still stand, and the handover can be resent with its original steps intact. Delivery disputes shrink to the message layer, where mail logs and the resent link close the question quickly.
Does an on-time record help if the client approved late?
Yes: the record separates your delivery time from their decision time, each dated. Late approval stays visible as late approval instead of being rewritten as late delivery.
By Brennan Zambo, founder of Zambo.
Last verified: 2026-10-17.
Try a handover
A handover gives your client one proof link with verifiable receipts to review, then Accept or Flag.
try it: say 'use zambo to hand this over to <client>' in your ai