Reset cell based on other cell contents

Hello and thank you for any help!!

I am working on a PTO spreadsheet. The last piece missing is being able to reset the PTO Used column "C" to "0" if the employees anniversary date "H" is equal to "True". Column "C" cannot contain a formula since PTO taken will be manually entered there.

Background info: Employee's earn a particular amount of PTO to use throughout the year. It does not rollover or accrue, and resets to whatever they are allotted based on years with the company on their anniversary date. All that works in the spreadsheet, but I need to 0 the amount taken on their anniversary date as well.

Thanks again!!!
TY