Rental Property

I have a rental property.  The landlord (home) insurance cost from 6/18-6/19 is one price ($750) and from 6/19-6/20 is a different price ($850).  Do I need to calculate the cost per month for both years and figure how much the cost was for 2019 or is my expense what I pay in the tax year I'm filing  (6/2019 for $750)?

 

Thanks in advance.