Me and my sister live with our parents. My mom does not work. Dad works and makes about $22000 a year. I have the same job and make about the same. Until 2025, my sister was a dependent on my father's return. We don't get health insurance through the job so we get it through Healthcare.gov.

As we started filing new healthcare application for 2026, there is a new income requirement to be at least equal to FPL. While I am fine, my father's income is below FPL for a household of three people.

I suggested that starting 2026, I can bring my sister in my tax return and claim her as a dependent. She is 17 years old. She will turn 18 in 2026 June. This would allow my parents to have a household size of 2 and with the income will be just above FPL for two people. This will make both parents eligible for Advance premium tax credits.

Is there anything legally wrong here from tax perspective?