This issue usually occurs because the correct leaver process was not carried.
Check that the correct leaving procedure has been carried out for this employee.
If there are further issues, please raise a new case online and reference the title of this article and please include details of the employee affected.
Note: If the Final Run indicator has been enabled and the Generate Salaries and Allowances (PAY290) job has been run then the PAY290 will need to be re-run without the Final Run indicator enabled so that the employee can be rejoined.