Check If 2 dates (or any dates in between) fall in Tax Year

I want to create a function that will check 2 user input dates (and anything in between) to see if it lies in a defined tax year.

I will define the tax year in Cells A1: 6/4/2009 and A2: 5/4/2010
and ask the user to input dates in Cells B1 and B2 to check if any of these dates (or anything in between) falls between A1 and A2.

For example: Tax Year is 6th April 2009 - 5th April 2010, Cell A1 is 6/4/2009 and A2 is 5/4/2010. User inputs 2nd March 2009 in Cell B1 and 10th May 2009 in B2. Because the 10th May falls in the tax year the output should be "True"

I can Excel to check one user defined number (Cell B1) using this =IF(AND(B1>=A1,B1<=A2),"Yes","No") but not sure which route to take to check 2 numbers B1 & B2 and anything in between.

Any suggestions would be more than welcome.