Nested IF Statement

[FM1]

Hey everyone. I am working on a resource model for my company. Essentially it is a list of contractors in the company with their daily rates and start and end dates. I have attached a sample spreadsheet.

As you can see, all the information has already been populated with the cost of each contractor per month (formula used - daily rate*18.83 [days worked per month]). It is also dynamic so if for some reason a contractor end date is changed it needs to be reflected on the cost per month columns (thanks mobidv).

Now the only issue is that the formula will calculate the cost for a contractor for a full 2 months even if they have only worked for 1.5 months (example of row 4). So basically the formula needs to change so if someone has not worked for the full month, it needs to be reflected in the cost so they are billed only for the number of weeks they worked for the month. Each month is based on 18.83 work days.

Any help is greatly appreciated.

Thanks.