The supervisor is leaving. Preserve the job knowledge first.

The person who remembers the job is moving on
Suppose your supervisor has accepted another role while a final account remains disputed. They remember the access problems, changed instructions and meetings. The office has invoices but cannot explain several disputed dates.
Arrange a focused handover while the supervisor is available. The purpose is to locate and understand existing information, not to produce a statement that supports whichever version the business prefers.
Start with unanswered factual questions
List the events that need clarification: who attended a meeting, which instruction was received or where an inspection record was saved. Ask the supervisor to distinguish what they personally saw from what someone else told them.
Do not fill gaps with leading suggestions. If the answer is uncertain, record that and identify any diary, email or photograph that could help. Uncertainty is part of an accurate handover.
Find the records before access changes
Identify business documents held in authorised systems, project folders or work devices. Transfer them through the normal business process, retaining originals and useful context.
business.gov.au says digital records need to remain accessible and under your control. Test that an authorised replacement can open the relevant files. A list of folders is not enough if the only working access will disappear on the last day.
Source: business.gov.au: Record keeping
Keep a later account clearly dated
A handover note written now is not a diary entry made when the event happened. Identify its author, date and the documents reviewed. Let the supervisor correct the note if it does not accurately reflect their explanation.
If formal witness evidence may be needed, ask the legal adviser how to proceed. Do not draft a statement for signature that mixes personal observation, office assumptions and legal conclusions without distinction.
Agree how follow-up will work
Record an appropriate contact route with the person's agreement and explain who will handle any later enquiry. Do not promise that a former employee will remain freely available or assume access to their personal files.
Name the person taking over the account. Give them the chronology, remaining questions and document index, so the customer does not receive a new and inconsistent explanation after the departure.
Resolve the gaps that matter to payment
Check whether the handover answers the disputed questions. Some gaps may be minor; others may require a missing instruction or independent assessment. Prioritise those that affect the amount or next decision.
For an ongoing commercial dispute, bring CRP the account history and the evidence you have located. Use Report a Dispute below. Say which points remain uncertain rather than presenting a departing supervisor's recollection as a guaranteed outcome.