@taxsavvy
There are different definitions of MAGI for different purposes. "Modified" adjusted gross income means modified for purposes of whichever test or benefit you are looking at. MAGI for a health insurance subsidy may be different that MAGI for retirement contributions, for example.
If you pay your parent as a household employee, you must issue a W-2 although you are not required to withhold any taxes, including social security and medicare tax. Your parent is not required to pay those taxes (or self-employment tax) on their tax return. However, they don't get credit in the social security system for retirement, medical or disability benefits.
