We are purchasing an Easement from an individual who is refusing to provide more than the last 4 digits of their social security number.  Since this is a real estate transaction, all amounts are reportable.   I am not quite sure what to do in this situation.

1.  Withhold a percentage of the payment?

2.  Obtain an explanation in writing?

3.  Accept the incomplete number and request another W-9 when a B Notice is sent? 

Combination of the above?