I already filed my returns, but got a 1099-R form in the mail. Line 2a taxable amount is zero. And the distribution code is is G. What am I suppose to do now?

[AmyT]

The practical answer is that, since a rollover (indicated by code G as the distribution code) will not affect your taxable income or income taxes, and there is no need for you to file an amended return.  Do keep the 1099-R with your other 2016 tax records.

Please be aware that, due to the IRS matching system, you may receive a notice.  If this does happen, you can respond with a simple letter that states that the 1099-R does not affect your taxable income so no amended return was filed and send that back with a copy of your 1099-R.