Figure out 6 months left, 3 months left, from a date

[Carlos5]

Hello,
I am trying to set up a "flag" that will tell me when a date will expire (two years from the original date.) i.e. date is 5/15/21 and it expires in two years on 5/15/23. I would like to set a tag that shows when it is 6 months to expiry and 3 months to expiry (based on the current date.) I can't make the logic work. In text I think like this: If today minus 6 months is greater than 5/15/23 than say "6 months to expiry", if today minus 3 months is greater than 5/15/23 than say "3 months to expiry" and if today = or is less than 5/15/23 than say "expired".
I hope that makes sense and someone can help me.
Thanks,
Carlos

 

[Phuoc]

Try this:

=LOOKUP(TODAY(),EDATE(A2,{0,18,21,24}),{"","6 months to expiry","3 months to expiry","expired"})

 

[Carlos5]

Try this:

=LOOKUP(TODAY(),EDATE(A2,{0,18,21,24}),{"","6 months to expiry","3 months to expiry","expired"})

That looks like it did the trick. Thank you!
A couple of questions if you don't mind, so I can learn a little. 1.) what does the lookup function do in this case, why is it needed? 2.) what are the "{ }" brackets used for and why not the usual "( )"?
Thanks again!
Carlos