For consultation, organise records identifying ownership, the transaction, receipt of proceeds and their subsequent movement. The precise government requirements must come from current instructions.
Distinguish forecast from completion
Label draft agreements, valuations and expected payments clearly. Once a transaction closes, update the chronology with actual dates and supporting records. Do not replace originals with an unexplained summary, or assume a sale agreement alone explains funds that passed through several owners or accounts.
Distinguish clearly between what is forecast and what has completed, because a file that mixes the two invites the assumption that a proposed transaction has occurred. Before a sale, the relevant records are an appraisal or agent's appraisal, the title or ownership documents, any charge over the asset and its outstanding balance, and an estimate of costs and tax — all plainly labelled as estimates with their dates. After completion, the records are different in kind: the executed agreement, the settlement statement, the discharge of any charge, the professional invoices and the bank credit showing net proceeds.
Keep the two sets separate and dated. Where a forecast figure later turns out to have been optimistic, having it clearly identified as a forecast is what prevents the discrepancy from becoming a credibility problem.