Get your taxes done using TurboTax

Since it's the same policy number, you should enter it as one single 1095-A form in TurboTax. You will need to adjust the monthly rows to show who was on the plan during which months.

1. Delete the duplicate: Go to Tax Tools > Tools > Delete a form and remove both 1095-A entries to start with a clean slate. 
2. Start one 1095-A entry: Enter the policy information exactly as it appears in Part I.
3. The "Shared Policy" Checkbox: When the software asks, "Was this policy shared with someone who is not on your tax return?", check YES.

Allocate by Month:

1. For Jan–March: You will allocate a percentage to your son (e.g., if there were 2 people on the plan, you might allocate 50% to him and 50% to you).
2. For April–May: Since he wasn't on the policy, you allocate 0% to him and 100% to yourself.
3. For June–Dec: Switch back to the shared allocation (e.g., 50/50).

How to handle the "Manual" Monthly Entry

1. TurboTax often asks if the amounts were the same every month. Select "No." This will open a grid where you can see January through December.
2. For your return: Enter 100% of the values for the months he was not on the plan, and your agreed-upon percentage (e.g., 50%) for the months he was on it.
3. For his return: He will enter the same 1095-A info but only enter values for the months he was covered (using his percentage), leaving the other months at $0.

A "Safe Harbor" Shortcut (Since APTC is $0)

If your son is not claiming the Premium Tax Credit on his own return (for example, if his income is too high or he doesn't need the credit), you can often simplify this significantly:

Report the entire 1095-A on your return and do not mark it as a shared policy. Since there were no advance payments to "reconcile," the IRS primarily cares that the 1095-A is accounted for. If you paid 100% of the premiums and he isn't claiming a credit, claiming 100% on your return is generally acceptable and avoids the "shared policy" math headache.