Tang Minh Ly, a 38-year-old former Navy warrant officer from Vietnam, is looking forward to his most "light-hearted and relaxed" lunar new year holiday in six years -- although it will alsobe his first away from home

The new year observance, called Tet, will begin Monday and is the most important holiday for the Vietnamese people.

A year ago Ly was deep in preparations for a perilous escape from Vietnam. Ten days after the Tet holiday began in 1981, Ly, with his wife, two small children, now 6 and 8, and 75 of their countrymen, fled by boat with Ly at the helm.

Now, he says, "I'm very excited about my first Tet in the United States. It certainly does not match the one in my homeland. I have to face some difficulties in my new life here. But for me this is the most lighthearted and the most relaxed Tet since the Communist takeover of South Vietnam.

"But whatever joy I have here, I still miss my parents in Vietnam and my homeland," he added.

His wife, Thu Ba, points out that the family will "observe Tet very simply this year," not even spending money for banh chung, a traditional holiday rice cake.

"The money we get is just enough for us to live on," explained Tang Minh Ly, who as a newcomer to the United States was a special guest at a Tet party given last week by the Vietnamese Navy Veterans Association. The Lys, who live in Silver Spring, receive $377.80 a month in welfare assistance and $160 in food stamps. Both are studying English so that they can find jobs.

Hoang My Hien of Annandale can understand how the Lys feel.

"I felt very sad during my first Tet in America six years ago," recalled Hien. She said she and her family and several friends spent that first American Tet together, in low spirits, worried about their future and finding jobs, and lonely for the home they had left behind.

This year, they will all gather again and, in a custom learned in the United States, each family will bring a dish.

For the nearly 15,000 Vietnamese living in the Washington area, Tet marks everyone's birthday as well as the new year. It is a time of celebration and the welcoming of spring, as well as the season for families to visit and care for the ancestral graves. Of deeper significance, Tet is dominated by the firmly rooted concepts of fortune, propitiation of the gods and the ancestors.

Calculated according to the lunar rather than the Gregorian calendar, the first day of the new year always falls sometime between late January and early February. Each year is assigned to one of the 12 animal symbols of the Vietnamese zodiac, arriving in this order: mouse, buffalo, tiger, cat, dragon, snake, horse, goat, monkey, rooster, dog and pig. Next Monday will usher in the year of the dog, one generally expected to bring good luck, although the fortunes of individuals may vary according to how their own zodiac signs mesh with the the dog, according to a Vietnamese astrologer.

Because of its deep spiritual significance, Tet is the time when Vietnamese refugees here most long for home, and when many pay special attention to traditions and rituals. For weeks in advance, many prepare special foods such as the traditional cake made of sticky rice, with pork, eggs and green bean paste inside, and a variety of preserved or pickled foods.

Seven days before Tet, a food offering is made to the kitchen god, who will make his annual report to the Jade Emperor of the universe, according to legend. Custom calls for the entire extended family to congregate at the family altar on the first day of Tet to thank their forebears for their existence, and request the traditional blessings of happiness, prosperity and longevity.

Superstitions connected with the holiday abound, and many seem to have sprung from a need to live in harmony with one's family, friends and environment. Before Tet, debts must be paid off, mistakes forgotten, offenses pardoned and faults corrected. Hospitality and friendship must dominate the three-day celebrations, and conflict and anger must be avoided.

Because happenings on the first day of Tet are thought to affect the coming year, many Vietnamese observe traditional taboos. No one must visit another's home on the first day of Tet, unless asked, because that initial visitor is thought to determine the luck--or misfortune --for the host family during the entire year.

Some Vietnamese interviewed last week said, only half jokingly, that they want to take off work on the first day of Tet so that they will not be burdened by hard work for the rest of the year. But a Springfield Xerox technician quipped, "I want to go to work on that day in order to have work around the year and not get laid off."

Tet has a festive side. Homes, shops and businesses are decorated with flowering apricot, peach or cherry branches, flowering narcissus plants and yellow chrysanthemums. Fireworks are set off and parades featuring the Vietnamese unicorn dance are held.

Each person wears new clothes, and good wishes are exchanged. Gifts of new money carefully folded in specially made small red envelopes are believed to bring good luck during the year.

Although most of these customs are maintained by Vietnamese residents here, the ways of celebrating have changed somewhat.

Hoang My Hien, a social worker in Arlington, said most Vietnamese celebrate more simply than they did in Vietnam, with fewer visits to friends and relatives, fewer vists to pagodas on the eve of Tet and fewer days off from work.

As an example, she described her own holiday plans. "I have sent greeting cards for Tet to friends and relatives. My family will recite prayers in front of the ancestors' altar before dinner. I will not make rice cake but I will have some Vietnamese marmalades," she said.

Hien, who wore a hand-embroidered, purple ao dai, a traditional Vietnamese dress sent by her mother in Vietnam, said she would take two days off work to honor Tet, instead of the customary three days.

At Pulsecom, a telecommunications company in Falls Church, 20 Vietnamese employes petitioned their employer for time off to observe Tet. The firm agreed.

Nguyen Trung Giang, the father of five children, two of them born in the United States, said, "I usually take vacations twice a year, one in summer with the children and one at Tet." He allows his children to stay home from school on the holiday, but added, "I don't force them."

Conditioned by years in the United States, the smaller children do not know as much about Tet as about Christmas, said Giang, a computer technician employed by Hughes Aircraft Co. in Arlington. "But they like Tet since on that day I keep the practice of li xi (giving money) in small red envelopes," he added, grinning and pointing to his wallet pocket.

Another indication that Vietnamese residents, who began arriving here six years ago depressed and bewildered after the fall of the South Vietnamese government, are more optimistic about their lives now is the number of public events that began earlier in the month and will lead up to the first day of the new year Monday.

The Council of Vietnamese Associations planned an arts festival, a Vietnamese movie showing, a poetry contest, a special broadcast, a fair and a reception. A shipment of magazines and money also has been sent to refugees still in Southeast Asian camps. The Vietnamese Navy Veterans Association, the Vietnamese Lawyers Association and other groups have held parties and dances.

In addition, an invitation-only reception is planned next week as the Vietnamese community's thanks to persons and governments who have aided refugees. Guests will include prominent U.S. government and congressional leaders, representatives of nations that have provided first-country asylum or have resettled refugees, and guests from private organizations that have helped Vietnamese

New Year events for the remainder of the month:

Tet Fair, Cafeteria, Kenmore Intermediate School, Arlington, Saturday, 10 a.m. to 5 p.m.

Vietnamese Folk Opera, Fairfax High School, Fairfax, Saturday, 7 p.m.

Tet Fair, Montgomery Blair High School, Silver Spring, Saturday, 10 a.m. to 3 p.m.

Cultural performance, Montgomery Blair High School, Silver Spring, Saturday, 3 p.m.

Traditional service in honor of the ancestors, Kenmore Intermediate School, Arlington, Saturday, Jan. 30, 11 a.m.

Radio broadcasts welcoming the new year, Sunday:

WHFS, FM 102.3: (in Vietnamese). 9-10 p.m.

WETA, FM 90.9: (in English). This broadcast is to introduce the Tet customs to the local American community, followed by an interview with four Vietnamese community leaders. 11:30 p.m. to midnight.

WETA, FM 90.9: (in Vietnamese). Special New Year's Eve broadcast. Midnight to 1 a.m. Vu Thuy Hoang is a Washington Post library staff member. Diana G. Bui is with the Indochinese Community Center in the District.