Due Dates Based Upon 2 Fields

I'm creating a db that provides project listings in the work queue, along with the due dates and a bunch of other data.

I have created a table [recurring projects] that stores the projects that are done frequently. Once I do some field manipulations on this table, I append them to a master table with all projects [projects] - ad hocs, non-recurring, etc.

Most, not all, recurring projects are due 14 days from the date of assignment, however it varies. I've created a query that populates the due date 14 days or whatever the user has inputed for working days from the assignment date.

All works good with this functionality.


Here's my problem:

There are some projects that are due on the 1st, 15th or some designated date each month. Typically the projects are assigned a due date prior to the month due (i.e. February projects are assigned in January). Since the due dates change each month, is there a way to code a query to look for the first process - 14 days - and if it is null, then populate with a day of the month due.

For example, the field [days_to_complete] = 14 so the query will populate 14 days from 1/31/07 resulting in [due_date] = 2/14/07 OR [days_to_complete] is null, but [day_of_month] = 1 , which I need to create the [due_date] = 2/1/07

I'm racking my brain and pencils are being cracked!

Thanks,
Nathan