WASHINGTON — For five years, congressional Republicans have taken out their anti-tax wrath on the Internal Revenue Service, cutting its budget by nearly $1 billion, reducing its staff by about 17,000, and even threatening to impeach its chief.

Now they say no one at the agency receives a bonus until customer service improves. And that measure, which the Republican-controlled House easily passed Thursday, was just one of six anti-I.R.S. measures that it approved this week, mostly by party-line votes, to mark the annual tax-filing deadline.

To supporters of the agency — and there are some — years of such attacks have yielded exactly what Republicans seemed to want: a depleted, defanged tax collector.

“I’m appalled, that’s all I can say,” said Lawrence B. Gibbs, a tax lawyer at Miller & Chevalier who joined the I.R.S. during the Nixon administration and was President Ronald Reagan’s choice for commissioner in 1986. “It’s fine to demonize the I.R.S. It has always been a target. Listen, that goes with the job.”