TaxGuyBill- thanks. Yet, a potentially confusing issue because TuroboTax instructions simply say you must include dependent's income in MAGI if "required to file a tax return and is filing a separate tax return. [presumably, for any reason]" Healthcare.gov website says something similar. However, I see that IRS instructions for form 8962 (Premium Tax Credit) say you only count income of dependents who are required to file an income tax return "because their income meets the income tax return filing threshold." I assume this is the basis for your view? And in above example, although $750 of self-employment income would require filing a return per IRS rules ($400 threshold for self-employment income), I assume your view is that the form 8962 IRS language also suggests no need to include the dependent's income here (because IRS language refers to $12,000 overall income threshold not self-employment income threshold)?
