The foreign policy team of President-elect Ronald Regan has begun compiling an inventory of options as part of "a zero-based approach" to the problem of the American hostages in Iran, which Reagan appears likely to inherit on Inauguration Day.

Sources in the Reagan camp, while saying that no decisions have been made, suggested that the consensus of senior advisers favors a lower-temperature policy designed to improve the bargaining position of the United States in the long run rather than a high confrontation effort designed to bring an immediate day of reckoning.

The captivity of the 52 Americans begins its 15th month today with Iranian authorities considering the Carter administration's third, and probably final, full-scale response to Iran's announced conditions for the hostages' release. State Department sources said there was no authoritative word yesterday from Tehran about the official reaction, but reports of intense political infighting there seemed to underscore the doubts in Washington that the latest U.S. proposals will be accepted.

In view of the Iranian parliament's action on Nov. 2 adopting mostly financial conditions for the hostages' release and the ensuing indirect negotiations through Algerian emissaires, the Carter and Reagan teams had been encouraged to hope that the long ordeal of the Americans would be ended before the change of government here. A settlement of the hostage problem would have freed the incoming Reagan administration from a powerful constraint on American freedom of action in the Persian Gulf and elsewhere, and eliminated an issue that has often preoccupied both the public and the top rank of government in this country.

As the talks dragged on, the Carter administration adopted a policy of making certain that its negotiating position with Iran did not impinge on the freedom of action of the incoming Reagan administration. As early as Deputy Secretary of State Warren Christopher's trip to Algiers on Dec. 2-4, Iran was cautioned that the U.S. proposals were subject to review and possible withdrawal by the new administration if a deal were not struck by Jan. 20.

This U.S. position was made more explicit and more pertinent last week when the message carried to Tehran by the Algerian emissaries specified Jan. 16 as the final date on which Iran could accept the American proposals. The date was selected, according to a senior Carter strategist, because it will take time to implement the complex administrative and legal arrangements currently offered by the United States in return for the hostages' release.

The crucial matter, according to this source, is that the hostages must actually be released by noon on Jan. 20 if the Carter commitments are to apply.The outgoing administration, by drawing a clear limit in this fashion, is seeking to avoid a situation in which the details and interpretation of U.S. commitments are still under negotiation when the officials responsible for them are out of office.

Sources in both camps said the Carter administration's clear statements of the time limits on its proposal were undertaken without any prompting from the Reagan camp. While the State Department has briefed Reagan's senior policy advisers on a regular basis about the course of the Iran negotiations, the Reaganites have been very circumspect, in a posture of simply listening without offering comments or suggestions, the sources agreed.

Reagan has received daily briefings from his foreign policy aide, Richard V. Allen, or other sources, but he has yet to sit down to a full dress review of the Iranian problem, according to those close to him.

In preparation for such a review and the beginnings of policymaking, Allen in the last few days ordered the compilation of an inventory of potential options for dealing with the problem after Jan. 20. The inventory is reported to include policy papers and suggestions from a number of Reagan foreign policy advisers as well as a more extensive effort to gather pertinent facts and assessments from officials of the Carter administration.

If the hostages are not released by then, an immediate issue facing Reagan on Jan. 20 will be whether to endorse the proposals made to Iran by the Carter administration, to withdraw them temporarily for a period of study, or to repudiate them. Discussions with several Reagan advisers suggest that, at a minimum, the incoming administration is likely to suspend the negotiations for a period of study unless Iranian acceptance of the Carter terms is seen as imminent on Jan. 20.

During the months leading up to the U.S. presidential election, a consensus of Reagan foreign policy advisers favored pursuing a "back burner" strategy for the hostage problem, according to several sources in the Reagan camp. Those taking this position maintained that the open U.S. eagerness to negotiate a settlement had encouraged Iran to seek a high price for return of the Americans, and perhaps stiffened the position of those in Iran who oppose a settlement.

Because of a belief in growing pressure within Iran to settle the problem as well as a look at the formidable domestic and foreign headaches facing Reagan in his early months, a U.S. posture that places the onus of bargaining on Iran has appeal in the Reagan camp. Arranging this, however, remains easier said than done.

Reagan's early campaign rhetoric criticized Carter for being too conciliatory and sometimes suggested a U.S. ultimatum that Iran release the Americans by an unspecified date. More recently, Reagan's verbal assaults on Iranian "criminals," "kidnapers" and "barbarians" suggested a tough line. But at no time did Reagan say explicitly what he would do as president.

A U.S. declaration of war against Iran, an action proposed early in 1980 by retired U.S. diplomat George F. Kennan, is among the potential options for Reagan. Kennan, who still favors this plan, said in a telephone interview that it could lead to internment of Iranian diplomatic personnel remaining in this country and arrest of Iranians publicly sympathetic to the Islamic republic as enemy aliens, as well as seizure (as opposed to the current freeze) of Iranian governmental assets here. Such actions could give the United States more leverage, in this view.

Kennan said it would be important for the United States to stress that it is not starting a war against Iran, but merely "recognizing a state of war" that Iran had created by seizing and holding the Americans. Kennan conceded that such U.S. action might endanger the lives of the hostages, but said that their continuing captivity could well impair their health in any rate.

A declaration of war would imply, though it would not necessarily require, U.S. military action against Iran. The problem is, according to several analysts of the situation, that failure of Reagan to follow a declaration of war with powerful action would lead to criticism at home of a "phony war" that could become more pointed the longer that the war was not "won."

With or without a declaration of war, U.S. military action to impose greater penalties on Iran for continued holding of the hostages is among the options often discussed. Several advisers in the Reagan camp expressed skepticism that the United States in is current military posture is positioned to take such steps and follow them through to their logical conclusion. And having tried and failed in a commando raid to rescue the hostages, a repeat of this action is now even more difficult, the advisers said.

Other options include the imposition of increasing penalties on Iran in other ways, such as further tightening of the international embargo, U.S. covert action to cause greater trouble in Iran and a U.S. tilt toward Iraq in its war with Iran. All have obvious difficulties in implementation and strategic impact. For example, European allies are reluctant to tighten the screw again while Iran is at war, Israel is strongly opposed to any U.S. connivance with Iraq, and strategic thinkers in several capitals are leery of anything that might push Iran into the Soviet camp.

A fundamental problem is the safety of the hostages. If their safe release continues to be the U.S. objective -- and public opinion pools show that this continues to be the overwhelming priority concern of the general public -- actions that undermine the stability of the regime in Tehran may be counter-productive. Outbreaks of internal bickering within Iran have seemed to retard the chances for the release of the hostages on several occasions in the last 14 months.

Reagan advisers suggest that U.S. objectives as well as strategy and tactics should be restudied in considering a course of action for the new administration. "We are going to take a zero-based approach, to look at the entire record carefully and prudently," said a member of the Reagan team.

Strategists in the outgoing and incoming administrations are painfully aware that unpredictable and essentially uncontrollable actions within Iran are as likely to determine the course of the hostage saga as anything decided by the United States. For example, an Iranian decision to put the hostages on trial -- a card the Iranians could play at any time -- probably would compel Washington to respond sharply, with more than words. Iran has been consistently warned about this since its first threats of trials in November 1979.

It would be much simpler for all concerned, officials of both administrations said, if the current course of indirect negotiations succeeds in the release of the hostages by Jan. 20. If he is forced to take over the Iranian albatross, Ronald Reagan is not likely to inherit any easy options.