To file a rectification request under Section 154 for TDS returns, the deductor should submit the request to the Jurisdictional Assessing Officer (TDS) if the error is apparent from record and pertains to processing or intimation under Section 200A or 154. The process is generally offline and involves submitting a formal application letter along with a copy of the TDS return, intimation/order under Section 200A, challan details, PAN details, and a detailed justification for rectification, including documentary evidence supporting the claim (e.g., revised TDS statement, correction justification report). It's advisable to first check with the TDS CPC portal (TRACES) or your AO if online rectification is permitted in your case, especially for PAN or challan mismatches.