Here's what I need to do: I need a formula that will look
at the SSN on sheet one match it to the SSN on sheet two,
when it finds a match then find the value in column R and
based on certain criteria, I need to add an if statement.
I'm not sure how to or if I can do a vlookup and an if
statement in the same formula.

example:

=vlookup(A1,Sheet2$A1:R1000,18,false), then based on the
data found, I need =if(Sheet2$R?="T","TMR","REG")

I know this is not the proper way to do this, and that's
where I need help. What is the easiest way to accomplish
this?