DEAR BOB: My husband is retired. All these years we have been apartment dwellers. Now we see the folly of this and wonder if it is too late to buy now. The snag is that although we have good income about $30,000 per year, total savings and investments of under $100,000, and with the stock market going nowhere, we don't know what to do. Jane P., Arlington.

DEAR JANE: Although you didn't give your ages, I presume you've got many years of good living ahead. Buying a house or condominium could be a wise move in the new year.

I can think of no reason you shouldn't buy, but there are many reasons you should buy, including (1) a hedge against inflation, (2) leverage benefits of mortgage financing (thus tying up little of your own cash), (3) protection against rapidly rising rents, (4) resale profit potential, (5) mortgage repayment in cheaper, inflated dollars worth less than today, and (6) income tax savings for property tax and interest deductions.

Buy with the smallest cash down payment possible. That way you won't be tying up much of your savings and investment money. With your strong retirement income, you should have no trouble getting a mortgage. When my elderly parents bought their condo a few years ago, they thought they were too old to be buying property. Now they realize it was the smartest investment they ever made.

DEAR BOB: I read that some mortgage lenders make "graduated payment loans." Are those good or bad for the borrower? Norma P., Bowie.

DEAR NORMA: Graduated payment mortgages (GPM) are good for the borrower. The idea is the payments start out at the "interest only" level until the borrower's income increases. Then the mortgage payments gradually increase to pay off the mortgage in 25 or 30 years.

For example, suppose the monthly payment on a fully amortized home loan would be $300 per month for 30 years. A GPM for the same amount, for 30 years, might start out with a $250 monthly payment, increasing to $275, and then increasing to $325 for the balance of the loan term.

FHA has been experimenting with GPMs and they've worked out very well. GPMs will enable many more people to qualify for home purchases than can qualify using the old, fully amortized home loans. Ask your lender for full details.

DEAR BOB: My realtor says that if I sell my home, where I have lived for seven years, my profit (about $72,000) is exempt from profit tax. This sounds too good to be true. Is it? Sarah, G., McLean.

DEAR SARAH: It's true if you meet the "over 55 rule" requirements. To qualify for the new $100,000 home sale tax exemption, you must (1) have lived in and owned your principal residence at least three of the five years before its sale, and (2) you must be 55 or older on the title transfer date. Your tax advisor has full details.

DEAR BOB: How big a down payment do we need to buy a home? Like many young couples, we want to buy a home but aren't sure if we can afford to do so. We don't have much cash for the down payment. James R., Washington.

DEAR JAMES: While it is possible to buy a home with no down payment on a VA mortgage, if you or your wife are qualified veterans, most home buyers pay at least 10 percent of the purchase price for the down payment.

However, FHA mortgages up to $60,000 require down payments of less than 5 percent of the purchase price. For full details on mortgage down payments, see your local bank, savings association, or mortgage broker.

Your realty agent can also suggest financing methods too. And don't forget that home sellers will often finance the sale at reasonable interest rates with no loan fees.

DEAR BOB: I keep reading in your articles about people who say they can't afford to buy a home. Why don't lenders make 40-year mortgages to reduce the payments so more people can afford to buy a home or condo? Bill W., Fairfax.

DEAR BILL: That's a great idea. However, most lenders can only make loans for 30-year maximum terms due to legal liitations. A law change would be required to make 40-year mortgages legal in most states.

DEAR BOB: Our new home is now under construction so we will be moving when it is completed. Should we wait to sell our present home until we have moved out or is it better to try to sell it while we're still living in it? Hubert M., McLean.

DEAR HUBERT: Sell your home while you're still living in it. Empty houses can be hard to sell as they make minor defects, such as small plaster cracks, appear huge. Only if your home doesn't show well with your furniture in it would it be wise to move out before selling it. Your realty agaent can make suggestions how to make your home attractive to buyers.

DEAR BOB: Is it true that prepaid mortgage interest is no longer tax deductible? What about prepaid property taxes? Joe M., Rockville.

DEAR JOE: Prepaid mortgage interest is no longer tax deductible. However, loan fees paid to get your personal residence mortgage are tax deductible as prepaid interest in the year paid. Property taxes can be prepaid and are tax deductible in the year paid. Your tax advisor has more details.

DEAR BOB: I'm interested in buying a home on a VA mortgage. Each time I suggest this approach with real estate agents, they try to discourage me by pointing out all the red tape and delays. How can I get details on VA mortgages? Robert M., Arlington.

DEAR ROBERT: Your local VA-approved lender, such as a bank, savings association, or mortgage broker, will be glad to give you full details on VA as well as FHA home loans. Check in the phone book yellow pages under real estate loans and start phoning to see which lenders make such loans and to set up an appointment.

DEAR BOB: I live in Saudia Arabia and I enjoy reading your articles in my hometown newspaper, The Washington Post. Upon my return to the U.S., I am thinking of buying a home in California. Please explain how Proposition 13 affects California property taxes. George A.

DEAR GEORGE: Many states are enacting laws similar to California's Proposition 13. In California all property is assessed at its 1975-76 assessed value. This value can be increased only by 2 percent maximum per year. If the property is sold, it is reassessed at the sales price value.

Annual property taxes cannot exceed 1 percent of assessed value, plus any bond assessments voted by local taxpayers. For esample, if you buy a $70,000 California home, your annual property tax will be $700 maximum. But homeowners pay less, due to the special homeowner's tax exemption.

Readers desiring the report, "How to Sell Your Home With or Without an Agent," should send 25 cents plus a STAMPED self-addressed envelope to Robert J. Bruss, P.O. Box 6710, San Francisco, Calif. 94101.