The requirement for employers to provide health benefits to employees is a cornerstone of the new law, but the new rules proposed by the Internal Revenue Service said that employers’ obligation was to provide affordable insurance to cover their full-time employees. The rules offer no guarantee of affordable insurance for a worker’s children or spouse. To avoid a possible tax penalty, the government said, employers with 50 or more full-time employees must offer affordable coverage to those employees. But, it said, the meaning of “affordable” depends entirely on the cost of individual coverage for the employee, what the worker would pay for “self-only coverage.”