The House Ways and Means Committee is showing signs of movement toward a possible compromise on President Carter's long-stalemated tax-cut plan - including a possible partial rollback of the 1969 tax increase on capital gains.

Behind-the-scenes negotiations among groups of committee members have turned up several possible variations of a compromise package, some of which might attract a majority.

Although committee sources cautioned it still is too early to be certain, some predict work could resume on the Carter tax plan as early as week after next.

The panel stopped work abruptly five weeks ago after it became evident that the president's proposal was heading toward a resounding defeat committee leaders had hoped to resume marking up the package early in May, but hit a snag over capital gains.

The capital gains squabble involves an amendment by Rep. William A. Steiger (R-Wis.) to repeal added taxes on capital gains that have totaled $2.4 billion since 1969. Conservatives are backing the provision, but Treasury and panel liberals oppose it.

The liberals have threatened to vote to scuttle the entire Carter tax-cut package if the Steiger amendment is approved. Steiger says he now has more than enough votes in the committee.

By far the most active compromise proposal on the horizon is a $15 billion plan by Rep. James R. Jones (D-Okla.), that essentially would replace Carter's package with a simple inflation adjustment in existing tax brackets and provide a graduated corporate tax rate sturcture to aid small business.

On capital gains, the Jones provision would go part way toward the Steiger amendment by reducing the maximum effective rate to 35 percent, rather than Steiger's 25 percent.

Capital gains are the profits from the sale of stocks or other assets.

It was not immediately clear whether Jones' provision would break the committee impasse over the Carter package. Jones said yesterday he believed he had a 20-vote majority, but Ways and Means leaders were taking a wait-and-see attitude. Treasury is opposed to Jones' plan.

Meanwhile, the Treasury continued to opposed any reduction in capital gains taxes, although committee sources said adminstration lobbyist did discuss several other options involving capital gains.

Jones had been asked informally by Rep. Al Ullman (D.Ore.), chairman of Ways and Means, to try to come up with a compromise that both liberals and conservatives could support. Jones, a conservative Democrat, had backed the Steiger amendment.

Apart from the capital gains provision, Jones' plan includes these basic elements:

Scrapping Carter's proposal for tax cuts for individuals and instead trimming individual income tax rates by about 6 per cent across the board, both by adjusting present tax brackets for inflation and by raising the $750 personal exemption to $1,100 or $1,200. In return, Jones would repeal the present $35 general tax credit enacted in 1975.

Jettisoning all Carter's proposed "tax reforms" save two: a repeal of deductions for state and local gasoline and personal-property taxes, and a tax on unemployment benefits for persons earning $20,000 or higher.