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HMRC internal manual

PAYE Manual

Individual records: merge individual records: automated merge processing

Automated merge consists of three processes

PAYE104010 Pre automated merge
PAYE104015 Automated merge
PAYE104020 Post automated merge

Automated merge processing will not require your input or involvement. This part of the guidance informs you of the system process that takes place prior to the creation of work items on automated merge failure and gives you an insight into what happens when a NINO / TRN are automatically merged.