I have a worksheet which has a date between Januarys to December. This
worksheet I m using for record sales and Concession form. According to new
rule sale against concession form should be submitted by concerned customer
1st quarter concession for should be deposited in next quarters 1st month.

For example
Date of Sales bill Expected Concession form
submission

1.10.2005 1.01.2006
2.10.2005
5.10.2005
2.11.2005
4.11.2005
2.12.2005
3.12.2005

How it can be formulated and calculated.

Thank and regards

Rao Ratan Singh