The current Capitol Hill fad for cutting spending stops dead when it comes to veterans' benefits, as the House proved yesterday by passing a budget-busting veterans' pension bill that would increase the program's cost by some $40 billion over the next 20 years.

As Rep. John P. Hammerschmidt (R-Ark.), said during debate yesterday on another bill to increase veterans' benefits, Congress has "always expressed a willingness and even eagerness" to vote for veterans' bills. In fact, they virtually fly through the congressional process.

Despite the fact that the pension bill would increase the cost of the program over current law from $2.7 billion in 1980 to $4.1 billion in 1980, and despite the fact that it was a major overhaul of the program, which Veterans' Affairs Committee Chairman Ray Roberts (D-Tex.) caffed "the most important bill brought to the House by the Veterans' Committee since I've been here," the bill was brought up under a process designed for non-controversial legislation, and passed by a 398-to-5 vote.

The only opposition to the bill came from Rep. Glenn M. Anderson (D-Calif.), who said he thought that the bill's bonus for World War I vets, in the form of $67 a month extra for each vet over 80, was not generous enough. Though it amounts to $804 a year for each pensioner over 80, Anderson said he wanted to give the 720,000 World War I vets, their widows and children, $160 a month, arguing that they did not get benefits other vets got, such as the GI Bill.

Budget Committee Chairman Robert N. Giaimo (D-Conn.) fought the increases when they were proposed in the budget resolution in May, but loss overwhelmingly. Yesterday he resigned himself to opposing only Anderson's attempt to defeat the bill so he could add more money.

The Veterans' Administration set the stage by urging the Veterans' Committee to adopt its "reform package," as the committee called it. But the VA package contained only $111 million in increases, in line with President Carter's budget. Though the president has railed against spending increases the White House has been silent on this bill, and, in fact, the Office of Management and Budget withheld a report from Giaimo estimating the cost at $40 billion over 20 years.

The House bill amounts to a 104.4 percent increase for a vet and his wife, and is about $825 million over Carter's budget. The Senate Veterans' Affair Committee has passed a bill that would cost $711 million the first year and allow a 68 percent increase for a married veteran.

Veterans' administration pensions are a form of welfare, and are different from veterans' compensations. Pensions are given to needy veterans who suffered nonservice injuries or illness, often many years after leaving the service. All needy veterans 65 or older get the pensions regardless of the state of their health. Compensation is paid only to veterans who suffered service-related injuries or illnesses.

Under current law, a veteran who is single gets $2,364 a year if he has no other income. A married veteran gets $2,544 a year. A widow with one child gets $1,908 yearly. But under the bill a single vet would get $4,000 a year, a married vet $5,200 a year and a widow with one child $3,900 yearly.

To get a pension under current law a vet's income must not exceed $3,770 if he is single and $5,070 if he is married.

Whenever Social Security benefits are increased automatically because of cost-of-living increases, the pension rate would be increased by a like percentage under the bill, to avoid a pensioner having his pension reduced because of Social Security increases.

To avoid slighting disabled veterans, the House also passed a bill to give some 2.25 million disabled vets with service-connected injuries or illnesses and some 325,000 widows and children of veterans who died in service a 6 percent cost-of-living increase. That will would cost $343 million a year or $1.7 billion over five years, and passed by a 400-to-1 vote.

Another bill, passed 385 to 16, would reduce from 50 percent to 40 percent the disability rating a veteran must have to receive supplemental aid.