Rising health-care costs and a climate of change brought about by the new federal health law are prompting American corporations to revisit the pact they've long had with employees over medical benefits.

Walgreen Co. is set to become one of the largest employers yet to make sweeping changes to company-backed health programs. On Wednesday, the drugstore giant disclosed a plan to provide payments to eligible employees for the subsidized purchase of insurance starting in 2014. The plan will affect roughly 160,000 employees,...