LESS PROFESSION TAX PAID IN 2020-21 COMPARED TO 2019-20

Dear Experts,

Received a mail from mahagst.gov.in Profession tax department asking for an explanation for 

LESS PROFESSION TAX PAID IN 2020-21 COMPARED TO 2019-20.

As due to covid19 and employee left the organisation, As a reduction in employees liability for P.tax is less.

Kindly guide how to reply to this mail. Simple writing is enough or has to provide some documents. (in this case which type of documents required).

Thanks in advance for your advice

Regards

Ajay