President Reagan is expected to propose a major restructuring of the government's health insurance program for its military personnel, retirees and their families in his fiscal 1986 budget.

The proposal, estimated to cut federal costs for the Civilian Health and Medical Program of the Uniformed Services (CHAMPUS) by $1.7 billion over five years, was outlined in a long-range health-options document being drafted in the White House for presidential counselor Edwin Meese III. The document said that unlike most other options in the document, on which no decisions have been made, the CHAMPUS changes will be in the budget.

Most of the $10 billion the Defense Department spends annually on health goes for military hospitals and clinics, where active-duty personnel and, in some cases, their dependents and retirees receive health care.

But part of it goes for the CHAMPUS insurance program used by civilian dependents of active-duty personnel and by retirees and their families for care in nonmilitary facilities. Under the proposal:

* For retirees and their dependents, the government would require that retirees pay $100 a year -- double the current amount, before CHAMPUS would kick in. The figure would be $200 a year for dependents.

The same higher deductibles would apply to dependents of active-duty personnel if they live within 40 miles of a military facility but choose to go to a nonmilitary facility. Those living beyond 40 miles would have no deductibles or copayments.

* The Defense Department could designate health plans, such as a prepaid health-maintenance organization, that beneficiaries in certain areas would be required to use.

* Hospitals would be forbidden to charge CHAMPUS patients more than is paid by Medicare for the same treatment, and private insurance companies that have sold health policies to persons entitled to military health benefits would be required to pay the government for care provided in military facilities.

* A new contributory dental plan would be added for dependents of active-duty personnel. In addition, families would receive protection against "catastrophic" costs resulting from serious illness: Families of active-duty members would not have to pay more than $1,000 annually, and families of retirees and survivors, not more than $5,000.

* CHAMPUS benefits, which now cut off when a military retiree reaches age 65 and starts receiving Medicare, would continue after age 65 to help cover costs Medicare doesn't, thus forming a sort of "Medi-GAP" policy.

In a separate section, the White House options document declares that there is a growing need for longterm care of the elderly and disabled, particularly because the elderly and very-old population is growing, but said: "With high budget deficits and with Medicare facing insolvency, the federal government should be careful to avoid committing additional funding to longterm care, especially through the Medicare program."