This wouldn't have been an issue for me, re: Nat Ins number since I don't have one, but requestion a SSN in the U.S. is such standard practice it wouldn't have occured to me to refuse to provide it! I'm such a sheeple!.

Thanks for letting me know it's not the same here.
God, I hate these stupid forms. We're already paying six months of rent upfront, do they really need to run a full reference check too? Gah!