Match a document to the year it actually covers
Retain the issuer, period, and correction information for income and other relevant statements. A current document may not explain an earlier year simply because it came from the same employer or account. When one source relates to more than one question, preserve that context. Identify missing material openly instead of substituting a number from memory that later appears to be a verified source fact.
Understand how the service uses those records
Ask which sources the particular filing or account task requires and who will review them. Confirm an appropriate recipient before exchanging private documents. Separating records by period supports accurate discussion but is not the completion of a return or an official submission. Keep drafts distinguishable from finalized material, and retain evidence when action actually occurs. The source collection should explain what is known and unknown, while the scope and current requirements determine which next steps need professional attention.