Sales pipeline formulas - if and then

Hi all,

Newbie in this forum.

I am building a sales pipeline where I have two types of charges: 1- one off charges , 2 - monthly recurring charges.

Using the below formula allows me to match the month of the expected sale in order to spread the monthly recurring charges over the 12 month period, however, if I have a one off charge, how do I add it in the formula? See attached pic as i couldn't upload any files for some reason.

Example:
test.JPG

=IF(F3>0,F3,(IF(MONTH(G$2)=MONTH($C3),$E3,0)))

thanks in advance.