A missing return and an unavailable document are different concerns. Mention both when asking for back tax help so the next service task can be explained.
Describe the absence you can observe
If a saved return cannot be found, record that as a missing copy rather than concluding that no filing occurred. If a copy is present but filing evidence is unclear, describe that second uncertainty on its own line. Later letters or account records may provide information requiring further interpretation. The list should state what you hold and what you cannot yet establish. It should not fill the space between those facts with an assumed filing status just to make the entry appear complete.
Assign different follow-up actions
Obtaining a copy and clarifying filing history may require different sources and questions. Note the relevant year and what evidence would resolve each gap. Keep any confirmation you obtain with the document or event it actually describes, preserving its date and identifiers. When calling about tax relief, explain both uncertainties if both remain open. Ask which one must be clarified before discussing the next action. A more precise list helps avoid repeating the same search while leaving the real filing question untouched.