Trying to use more than one IF statement in Excel

How can I combine two IF statement in Excel?

The first IF is checking a start date from one cell (OtherTab!$G6) and if that date is greater than or equal to a date in a cell on my active sheet (S1), I want it to execute a formula (OtherTab!$D6*SetupTab!$B$3))*S$2).

So this formula works for me to perform this function: =IF(S$1>=OtherTab!$G6,OtherTab!$D6*SetupTab!$B$3))*S$2

The caveat is that if an end date is past the date in the same S1 cell, rather than execute the formula, the cell value would just be zero.

So it would need to be something along this line, but this doesn't appear to be properly checking both of these IF values: =IF(S$1>=OtherTab!$G6, IF(S$1>=OtherTab!$H6 OtherTab!$D6*SetupTab!$B$3))*S$2

A little background/clarification on what I am trying to accomplish...this is a finance type report that will calculate expense per month for an employee. The main formula calculates the expense for me, but if an employee leaves the company, I no longer need to forecast that expense past their end date, which is why I want it to "zero out". Likewise, if I have a new employee starting in two months, but I want to get them on the books now to start to forecast them, I don't want their expense to start to calculate until their actual start date.

I really hope this is making some small amount of sense to someone out there :)