Representative Henry Waxman called the chief executive officers of AT&T Inc., Verizon Communications Inc., Caterpillar Inc. and Deere & Co. to provide evidence to support costs the companies plan to book related to the new health-care law.

Waxman of California, chairman of the House Energy and Commerce Committee, and subcommittee Chairman Bart Stupak of Michigan released letters they wrote to the executives, saying their plans to record expenses against earnings as a result of the law contradict other estimates. The lawmakers requested the executives appear at a hearing Stupak plans on April 21.

"The new law is designed to expand coverage and bring down costs, so your assertions are a matter of concern," Waxman and Stupak, both Democrats, wrote in the letters yesterday. "They also appear to conflict with independent analyses."

AT&T, the biggest U.S. phone company, is among employers that have announced plans to book costs related to the health- care law signed this week by President Barack Obama. The 10-year, $940-billion legislation is intended to cover 32 million uninsured Americans and provide benefits such as restricting premiums and ending the practice of denying coverage for pre-existing conditions.

Dallas-based AT&T, with local operations in Hoffman Estates, said in a regulatory filing yesterday it would record $1 billion of costs, the most of any U.S. company so far.

AT&T previously received a tax-free benefit from the government to subsidize health-care costs for retirees. Under the new bill, AT&T will no longer be able to deduct that subsidy.