Because they are in the hospital, the Secret Service agent and D.C. policeman who were shot Monday in the assassination attempt on President Reagan are not eligible for new, higher life-insurance benefits that go into effect today for most of the government's 2.7 million workers.

Regulations require that federal employes who last month elected to purchase more generous life insurance policies must be in an "official duty status" for at least a day on or after April 1 before the new policies become effective, according to officials of the Office of Personnel Management.

On a given day as many as 300,000 U.S. workers are off the job because they are sick, on vacation or taking leave without pay. None of them will be covered by the new optional insurance benefits until they return to work for one day.

Old life insurance policies -- providing much lower coverage -- are in effect and will remain so until each individual employes' new policy goes into force.

Because they are federal officials who are considered in a duty status 24 hours a day, both President Reagan and his press secretary James Brady are automatically covered by new insurance benefits if either of them signed up for the optional insurance before March 31. If the president signed up for all the optional packages available, his new federal life insurance coverage -- would be $565,000 straight life and $765,000 double-indemnity payment for accidental death.

Earlier this year the government announced a new insurance package. In addition to providing basic coverage that approximates an employe's annual salary, workers were offered the opportunity -- during the month of March -- to sign up for additional insurance that, for the typical civil servant, would pay up to five times salary (with a double-indemnity claus) as well as new insurance for spouses and children in lesser amounts.

But regular employes must be in a duty status -- not on leave, vacation or sick at home or in the hospital -- before that new insurance can go into effect. This is how the federal policy reads:

"Most civilian employes of the federal government and the District of Columbia are eligible to participate in basic life and one or more of the options. Generally, these coverages are effective the first day you are on duty and in a pay status on or after April 1, 1981, if you enrolled during the March open enrollment period.

"If you enter on duty as a federal employe after April 1, 1981, and enroll within 31 days, these coverages are effective on the first day you are in a pay and duty status. You must actually be on duty at your workplace and not on annual or sick leave, excused absence, or otherwise absent from duty."

It is not known how many federal workers are of duty this week. But officials say that as many as 300,000 could be out for one reason or another. Except in a few cases, none of those employes who signed up for new, higher benefits will become eligible for them until they return to work for at least one day.

Because of the insurance contract language, many federal agencies -- including the Secret Service -- advised employes who might be off this week for any reason to come in and be put on an "official duty status" for one day, so their coverage could go into effect. Many people will be coming back to work this week for that reason.

This would seem to be one of those times that Uncle Sam ought to bend his rules and cut his red tape -- at least for two of his people who are absent from duty today through no fault of their own.