Washington area representatives lost their fight yesterday to kill a provision in the massive House tax overhaul bill that would increase taxes on public employes' pensions.

Rep. Frank Wolf (R-Va.) won a token concession from the House Rules Committee, allowing him to restore the tax benefits for public employes in another bill sponsored by the Republican minority in the House. The Republican bill was offered as a substitute for the tax reform proposal passed by the Ways and Means Committee. The committee bill includes a provision that would eliminate a period -- up to three years -- when newly retired public employes can receive their pensions tax-free.

But because the Republican tax substitute was not given much chance of passing, Rep. Stan Parris (R-Va.) and Rep. Steny Hoyer (D-Md.) said the Rules Committee's action was insufficient.

The tax package has been an emotional issue in which House Republicans bucked the White House and refused to support the measure that President Reagan badly wanted. And the Democratic leadership has been pressing members hard to maintain a majority supporting the bill.

The situation put Hoyer, known for his loyalty to the Democratic leadership, in a politically uncomfortable position of either standing by his party or satisfying his federal employe constituents by voting for the Republican proposal.

Hoyer said he finally opted to vote against the Republican version and thus Wolf's provision to help public employes, saying that overall he preferred the Democratic tax plan. But he added, "We sent a very important message to the Senate." He said he believes the Senate will realize that the taxation of public employe pensions is a politically volatile issue and will change the House bill.

The House passed the Democratic tax measure on a voice vote; Hoyer had said he intended to vote for it, and Parris and Wolf said they planned to vote against. Rep. Michael Barnes (D-Md.) declined to say how he planned to vote.

Last week the House, in a surprise move, defeated a rule under which the massive tax overhaul bill would be considered. Wolf, Parris and other federal employe supporters spoke out against the rule, because it did not allow an amendment to change the federal employe section.

The GOP leadership immediately latched onto the issue and rounded up opponents to defeat the rule.

Yesterday several Democrats pointed out that changes in the federal employe provision was not one of the concessions the GOP House members demanded from the Reagan administration for the Republican turnaround in the House.

The rule passed in the House yesterday and it allowed the debate and vote on the Republican alternative tax measure. Parris and four Maryland Democratic representatives, Hoyer, Michael D. Barnes, Barbara Mikulski and Roy P. Dyson, voted against the rule, although Parris was on the list of 50 Republicans that the White House said had switched in its favor. Parris said he had no idea why they thought he was supporting the rule, because no one had asked him.

Wolf voted for the rule because he said that the concession by the House Rules Committee enabled the House to focus on the federal employe issue.

Maryland, which voted solidly against the rule last week, was split yesterday. Republican Reps. Helen Bentley and Marjorie Holt, and Democratic Reps. Beverly Byron and Parren Mitchell switched their votes. In Virginia, Republican Reps. G. William Whitehurst and Herbert H. Bateman switched their votes after hearing Reagan's personal plea Monday.

After the vote on the rule yesterday afternoon, Dyson teased Bentley, who was sitting in a room off the House floor. "You weren't even on the list of 50" that the White House said had switched their vote, said Dyson. "I hope you at least got something in exchange."

Bentley said that she waited until the very last minute to vote, and that if her vote could have meant the defeat of the rule, she would have voted "nay" instead of "yea."

"It's a bad bill," said Bentley. "It's antibusiness." But Bentley said she had received numerous calls from the White House pleading with her to support the rule and the tax bill.

"Some said 'please, please,' some said 'we'd like your help,' and some said 'vote for us or else,' " said Bentley.