My child was in school until May on our marketplace account, no income, graduated and got his own marketplace account and had income, do I include his income in my MAGI?

[AmeliesUncle]

Does he qualify as your dependent?  Are you claiming him as a dependent?

If yes, is his income over $15,750 or have more than $450 of non-job income?

[tinaspurgeon]

He is not a dependent on my taxes, he was a dependent on my insurance policy for the first 5 months. 

And yes, his income is above the threshold to file his own return.

[AmeliesUncle]

No, if he is not a dependent on your tax return, you don't include his income as part of the calculation for the Premium Tax Credit for Marketplace health insurance.

Because he was on your 1095-A for five month, both you and he will need to fill out the "allocation" information.  That will 'split' those amounts between your tax return and his tax return.  If Advance credit was received (column C of the 1095-A), you can allocate using any percentage (all three amounts need to be the same though).  It is usually most beneficial to allocate 100% to one tax return and 0% to the other.  Allocating 100% to the tax return that has the lowest number on Line 5 of Form 8962 will result in the best OVERALL credit.