Welcome to the forum, Wanda.
Let's assume you have the following layout, with data starting in row 2 to allow for headings.
Column A - invoice amount
Column B - due date
Column C - 0-30 days
Column D - 31-60 days
Column E - 61-90 days
Column F - over 91 days
Then your formulas would be:
Column C: =IF((B2-TODAY())<=30,A2,"")
Column D: =IF(AND((B2-TODAY())>30,(B2-TODAY())<=60),A2,"")
Column E: =IF(AND((B2-TODAY())>60,(B2-TODAY())<=90),A2,"")
Column F: =IF((B2-TODAY())>90,A2,"")
Hope this helps!