WASHINGTON—Following final congressional approval, President Bush Friday signed mental health care benefits parity legislation into law.

The parity provisions, included in a broader financial services bailout bill, passed the House earlier Friday on a 263-171 vote. The legislation, which the Senate had approved earlier in the week, will require health care plans to provide the same coverage for mental disorders as they do for other medical illnesses—a requirement that most group health plans now do not meet.

For example, plans no longer will be allowed to limit the number of annual outpatient visits for treatment of mental disorders while not imposing a comparable limit on the number of outpatient visits for other medical problems.

While the plan changes would be extensive, the cost impact is expected to be modest. The Congressional Budget Office last year estimated that enactment of a similar bill would boost health insurance premiums by an average of about 0.2% a year.

The measure will take effect Jan. 1, 2010, for most calendar-year plans.