When this guide is useful
A buyer asks for a lookback review covering several years and entities.
The distinction that matters
Separate issue identification, preparation, filing and follow-up. Each year, entity and state can require distinct work and factual support.
A worked situation to investigate
A planning proposal includes a prior-year review but the buyer assumes three amended returns are already included.
The example is illustrative. Begin with the underlying event and its source documents, then separate missing facts from disagreements about their treatment. Work through the checks below in the order that matches your file, rather than treating a completed checklist as a tax conclusion.
Build a traceable handoff
Identify the affected person, entity or property and the relevant period. Keep original evidence, corrections and the reviewer's written conclusion connected. If the facts change after review, preserve the earlier version and ask whether the change affects implementation.