House-Senate conferees agreed yesterday to split the difference between their two versions of the administration's oil tax. Their compromise would raise an estimated $227.3 billion during the next decade.

But they left until next year the specific decisions -- how to raise nearly $50 billion more than the Senate approved this week, and where to trim nearly $50 billion from the tax approved last summer by the House.

The compromise, if approved by the House and Senate once these specifics are worked out, would leave the government and oil industry splitting roughly 50-50 the expected proceeds from President Carter's decision to phase out government controls on crude oil prices.

That 50-50 split is of the proceeds that would be left after payment of all other, regular taxes. Counting these other taxes, oil producers would be left with about 22 percent of the anticipated $1 trillion in extra money that decontrol is expected to produce by 1990.

The decision to set a revenue total without specifying where the money would be drawn from was a surprise, prompting Sen. Bob Dole (R-Kan.) to complain that it was "like getting your dinner before reading the menu."

But House Ways and Means Committee Chairman Al Ullman (D-Ore.), leader of the House conferees, argued that the conference needed to make some "breakthrough" before heading off for Christmas recess.

And Senate Finance Committee Chairman Russell B. Long (D-La.), agreeing to the 50-50 split between the House and Senate taxes, said, "We can be here from now until February or March and still not get anywhere," on the overall figure, short of an exact split down the middle.

Sources on the conference committee said the administration went along with the compromise, although House Speaker Thomas P. (Tip) O'Neill (D-Mass.) quoted Carter earlier this week as saying he wanted to do more than just split the difference.

Dole suggested that the conferees were settling early on a total dollar figure to keep Carter from making political hay out of the fact that Congress has not yet passed the tax. "We're going to be attacked by the president whatever we do," said Dole. "This is nothing but proof the top dollar will win.It will get you headlines but it won't get you energy."

Carter aides tentatively endorsed the compromise last night, but stressed that the administration's finnal disposition toward the legislation will depend on how the money is to be raised.

Calling the conference agreement "an encouraging step forward," White House press secretary Jody Powell said that the $227.3 billion level is acceptable to the administration, but only if the application of the tax is "consistent with sound energy policy."

White House officials would not specify what revenue producers they would find acceptable, but Powell noted without elaboration that some exemptions from the tax would have a significant impact on energy production while other exemptions would have no effect at all.

He called the $277.3 billion "a good deal more than anyone would have predicted even a few weeks ago."

After Carter proposed the tax this year as he began the first phase of oil price decontrol, the House approved a tax that would yield an estimated $277 billion by 1990 -- close to what the president wanted.

In action over the last month, the Senate came up with a tax that would yield $178 billion over the same period. Its tax was lower principally because it would give favorable treatment to independent producers and to the production of newly discovered oil by the major companies.

When the conference gets down to drafting the compromise tax, it will have to choose between the independents and the majors -- or possibly split their burden -- in deciding how to increase the Senate bill by $50 billion.

The proposal to split the difference on the total size of the tax came from Ullman, and the House conferees endorsed it on a voice vote, with only two audible dissents from among Republican members.

The Senate conferees mustered only a bare majority for the compromise, with nine of their 11 members present and three of them voting against it, leaving only six in favor. The dissenters were two Republicans and Sen. Harry F. Byrd, Jr. (Ind.-Va.)

In outlining the proposal, Ullman said it was being made with the understanding that the details of the tax would be worked out "within the framework of a sound energy policy." He did not elaborate, although some conferees took that to imply there would have to be an equitable distribution of the tax burden between major oil companies and independents and consideration given to the overall impact on energy production.

What it meant, said Long, was that "we won't play games" in drafting the specifics.