One large group of Americans will be exempt because of their income. The law won't ask people to buy insurance if it will cost more than 8 percent of their earnings. Subsidies will keep many families below this "unaffordable" level, but the federal aid is phased out as household income rises. A family of four with $60,000 in income might be eligible for a federal subsidy under the ACA to buy insurance, and yet be exempt from the individual mandate.
High-earning Americans will be subject to the mandate, because the insurance costs will amount to less than 8 percent of their income.
If you are subject to the mandate and don't buy insurance, fines will be assessed through the tax code. By 2016, after two years of the mandate, the fines will be either $695 per person (up to $2,085 per family) or 2.5 percent of income, whichever is larger. (The fines are set at lower levels for the first two years. For example, in 2014 it's $95 per person or 1 percent of income.)
If you need to shop for yourself, the ACA will offer subsidies of two kinds. First, premium credits will help households with incomes of four times the poverty level or less. The second main subsidy would reduce the amount of medical copayments owed by insured individuals or families.