DEAR BOB: We've listed our home for sale at $56,000 with an excellent real estate agent. She has done a terrific job of promoting the house with ads, open houses, and multiple listing cooperation with other agents. Several offers have materialized. But for one reason or another a sale hasn't yet worked out. The most recent offer was for your full $56,000 asking price from a couple that wants to get a VA home loan. A condition in the offer requires us to pay their four-point "loan fee." In other words, the veteran buyer is getting our house for nothing down. We would have to pay his loan fee. The agent says this is customary. Is it? Curt F, Rockville.

DEAR CURT: Yes. FHA and VA mortgage interest rates are set by the government, usually slightly below the interest rate on conventional home loans. So banks, savings associations, and mortgage brokers charge a "loan fee" to bring their yield up to market interest levels.

By law, FHA an VA home loan buyers cannot pay more than a one-point "loan processing fee." So that leaves you, the seller, to pay any loan fee needed to get a VA or FHA home loan. If you accept that offer and pay the four points (four percent of the loan amount), such cost is deductible from your gross sales price as a selling expense.

DEAR BOB: Last year we made a $18,000 long-term capital gain on the sale of some land. When we had our income taxes prepared, the preparer said we couldn't use income averaging on long-term capital gains. I thought you said we could. Who is right? Yoland F., Falls Church.

DEAR YOLANDA: I am. Your tax advisor is mistaken. Fortunately, you can amend your tax returns to take advantage of income averaging of your long-term capital gain and gets a tax refund.

To see if your large profit is big enough to qualify for income averaging, your 1977 income would have to be at least 20 percent greater than your average income for the last four tax years. Going to another tax advisor might be advisable.

DEAR BOB: You often say that to defer the profit tax on the sale of a primary residence, the more expensive relacement home must be bought within 18 months before or after the sale (24 months if a new home is built). A friend at work says this rule also applies if I own a house more than 18 months before sale (now rented) and move into it after the sale. True? Ellsworth F., Washington.

DEAR ELLSWORTH: Sorry, but it's not true. To qualify for the residence replacement rule, you must buy and occupy the replacement principal residence within 18 months before or after the sale of your former primary residence. You can't qualify by moving into a residence you bought more than 18 months before the sale. See your tax adviser for further details on this wonderful tax rule.

The report, "How to Sell Your Home With or Without an Agent," is available for 25 cents in coin plus a self-addressed STAMPED envelope, from Robert J. Bruss, P.O. Box 6710, San Francisco, Calif. 94101.