Filed my last tax returns with Tax ID number. Last year I got a social security number and would like to use it for filing my current tax returns. Anything I should know before I file?

I read somewhere that if you file using a social security number for the first time when in the past you used Tax ID number you should enter $0 for AIG. I didn't find that option. The option to enter your AIG is when they ask your last year AIG to confirm identification when using e-file. Is that where I would enter $0?