PAYE46043 | Employer returns: employer return post capture: reviewing forms P38 and P38A (Action Guide)
From HM Revenue & Customs · PAYE Manual
When you receive a P38A or P38 form follow steps 1 - 4 below
On receipt of form P38A or P38
If the P38A or P38 accompanies the original P35 or P35MT (for years up to 2004) go to step 4
Otherwise
Obtain the P38 list and check to see if the employer has been entered on the list
Consider whether the P38 or P38A comes under the selection criteria for a potential employer compliance review. See the subject 'Form P38 Review' PAYE46040 for more details