Oct. 1: Open enrollment begins. People can begin shopping for insurance plans on the exchanges. Lower- and moderate-income people will be able to apply for tax subsidies to offset the cost of premiums or enroll in Medicaid in states expanding the program.

Jan. 1, 2014: Coverage obtained on the exchanges goes into effect. Most individuals are required to have health insurance. Penalties for those who fail to do so kick in, beginning at $95 a year per person, or up to 1 percent of a family’s income, whichever is greater. (The penalty will increase in future years.) The penalty for an uninsured child is $47.50. Insurance companies cannot deny coverage on the basis of preexisting conditions nor charge higher rates based on an applicant’s sex or medical history. Policies must offer a basic package of benefits.

March 31, 2014: Open enrollment period ends for the year. It will reopen in October 2014.

Jan. 1, 2015: Businesses with 50 or more workers must provide health benefits or pay fines.