If statement with a followup If based on the results of the first in the same cell.

I know the title didn't help a whole lot. Let me explain what i'm trying to do.

I'm working on spend tracking spreadsheet, and one of the clients rebates is based on spend per quarter. I'm using the following formula to look at today's date and determine what quarter the date falls in, and then provide the sum of that particular quarter.
=IF(TODAY()<=1/1/2017>=3/31/2017,SUM(D2:D4),IF(TODAY()<=4/1/2017>=6/30/2017,SUM(D5:D7), IF(TODAY()<=7/1/2017>=9/30/2017,SUM(d8:D10),SUM(D11:D13))))
This part of the formula works fine. I need to take the resulting sum and compare it against another table that compares spend level to the associated rebate level, and return the rebate level amount.

How can I build this into one cell so that my second function (another series of nested If statements) takes the results of the first section and compares it against the spend level table to return the correct rebate amount? I know I can use this result as a "helper column" for a second set of formulas, but if i can keep it in one cell I'd like to.

I'm surprised that the formula does produce the correct results, as this part:

=IF(TODAY()<=1/1/2017>=3/31/2017 ...

doesn't make sense. Nor do the other similar IF statements elsewhere in the formula. You need to write that part like this:

=IF(AND(TODAY()>=--"1/1/2017",TODAY()<=--"3/31/2017") ....

to determine if it is in the first quarter of this year, although it would be better like this:

=IF(AND(TODAY()>=DATE(2017,1,1),TODAY()<=DATE(2017,3,31)) ...

I think you need to get this right before thinking about the other part of your question.

Hope this helps.

Pete