For the United States to remain under the SALT II limits this fall after the USS Alaska, capable of carrying 24 Trident missiles, goes to sea trials, the administration would have to retire 14 land-based Minuteman III intercontinental ballistic missiles, not eight Minuteman IIs as reported yesterday.

The United States, in fiscal 1986, will exceed the limits of the unratified SALT II treaty, according to projected force levels contained in Defense Secretary Caspar W. Weinberger's annual defense posture statement.

The treaty, which was signed but never ratified by the Senate, would have limited both the United States and the Soviet Union to 1,200 strategic missiles carrying more than one warhead. A chart included in the Weinberger statement, which was released Monday, said that the United States would have 1,238 such missiles in fiscal 1986, 550 of them based on land and 688 installed on submarines.

"The chart was not designed toreflect arms control decisions not yet made," a Defense Department spokesman said yesterday. "The president has a variety of options" that would keep the United States within the treaty's provisions, the spokesman said. "This was not meant to be an arms control chart."

Since 1981, the Reagan administration has said that it would not undercut the SALT II treaty provisions as long as the Soviets followed suit.

The United States would breach the treaty's missile limit in October, when the submarine USS Alaska begins its sea trials with the capability of carrying 24 Trident ballistic missiles.

If the administration wanted to remain under the treaty limit, it could retire a Poseidon submarine, which carries 16 missiles, or eliminate eight land-based Minuteman II ICBMs.

On Jan. 10, President Reagan told a news conference that the administration was planning on "replacing older, less accurate missiles and submarines" as the new Trident submarines are launched.

Over the past 10 days, however, the president and some of his top advisers have said the United States may exceed the SALT II limit when the Alaska goes to sea because the Soviet Union has not been complying with its SALT II commitments.

On Jan. 26, for example, Reagan said he would "discuss whether we actually go above the SALT II limits when the next Trident goes to sea and in that regard, we have to take into consideration that the Soviet Union has, we believe, not stayed within the limits."

Last week, a senior Pentagon official said that "the administration had not faced the question" of whether to trade in missiles to remain in compliance with SALT II. He added that "it may not be faced" because the treaty runs out on Dec. 31.

In a meeting with reporters last Thursday, Kenneth L. Adelman, director of the Arms Control and Disarmament Agency, said the president's advisers would make recommendations in October on whether the United States should continue to adhere to the treaty. He said the Soviets were complying with some, but not all, of the treaty's provisions.