CFR have communicated an updated to the National Insurance Rates relating to persons born before 1961 - https://cfr.gov.mt/en/News/Pages/2020/Adjusted-Class-1-Social-Security-Rates.aspx
This update is retrospective from January 2020. Hence in your next payroll you have to calculate the difference in the NI for persons born before 1961. Adjustments can be entered as per below.
Please contact us to send you the updated NI Rates File.