DEAR BOB: Is the real estate sales agent's commission figured on the total property sales price or just on the equity tranferred? Our home is worth about $55,000 but we owe $37,800 on the mortgage. George D., Annandale.

DEAR GEORGE: Realty sales commissions are computed on the property's gross sales price regardless of the mortgage amounts involved. For example, a typical 6 percent commission on a $55,000 sales price is $3,300.

DEAR BOB: I own a condominium town house. What can be done if another owner doesn't pay his monthly maintenance assessment? Theo E., Alexandria.

DEAR THEO: Condominium law is developing fast. In most states, the condominium homeowners' association can file a lien on the defaulting owner's condominium unit. If he or she then doesn't pay, the lien can be foreclosed, much like a morgage. Consult a real estate attorney in the state where your condominium is located for further details.

DEAR BOB: What is the maximum GI home mortgage available? Is it true that it's only $60,000? Fred G., Washington.

DEAR FRED: The maximum GI home loan is whatever the bank, savings association, or mortgage broker will lend. The Veteran's Administration sets no limit. But VA won't pay more than $17,500 on a mortgage loss to the lender.

For this reason, many leaders set their GI loan limit at four times $17,500 or $70,000. But some VA lenders loan up to $100,000 and more. The current maximum mortgage now available through FHA is $60,000.

DEAR BOB: We've owned some vacant pasture land for about 14 years. Last year we built a house on one acre which we want to sell in 1978. If we sell it, will our profit be taxed as ordinary income or as long-term capital gain? Cliff R., Hagerstown, Md.

DEAR CLIFF: The minimum holding period to qualify for low, long-term capital gain tax on your profit is 12 months (nine months for sales in 1977 and six months for sales in 1976 or before).

So your profit on the land value will clearly belong-term capital gain. But your profit on the newly constructed house will be taxed as ordinary income if you see it within 12 months of construction. In other words, for tax purposes, there are really two separate sales: (a) the land value, and (b) the value of the house. See your tax advisor for further details.