It asked if fatca filing requirment box is checked on 1099-div - where do I find this box

On a traditional Form 1099-DIV, it’s to the left of box 10 (see 2017 Form 1099-DIV). 

If you received a 1099-DIV statement (as opposed to the form itself) from your payer, it should list “FATCA filing requirement,” and an “X” or some other such affirmation next to it if there’s a FATCA filing requirement.  If “FATCA filing requirement” isn’t listed, the payer isn’t indicating a requirement.