How does health care providers calculate income?

[nsmall]

How does health care providers calculate income?  I am planning to substitute teach for a little side money, but mainly be living off VTSAX, VTIAX, and the savings account once I FIRE.  Not sure if what I claimed for 2020 taxes for example matters?   Thank you in advance

[shuffler]

Search for "magi for aca" and you'll find articles like this:

https://www.healthinsurance.org/glossary/modified-adjusted-gross-income-magi/

Notably, the standard-deduction that people take on their taxes, charitable deductions, and mortgage interest deduction aren't included when determining ACA income levels.