Q: Would you advise older persons to take a mortgage on their houses for living expenses, or would you advise them to sell and put the money in Treasury bonds that yield 9 percen, and rent an apartment?

A: When you speak of taking a mortgage on your home, you may mean one of two things:

(1) Mortgage your home, invest the net proceeds in a liquid investment giving the greatest return with safety and live off the combined principal and interest, bearing in mind your mortgage payments, or

(2) Secure a "reverse annuity mortgage."

In the first case, the interest rate on the mortgage currently exceeds the return on the net proceeds you invest. In the second, a lender will pay you a stipulated sum monthly on the mortgage you execute until the agreed mortgage amount is consumed.

In each situation, you have a mortgage to pay off one way or another. (Incidentally, there are no lenders in this area presently granting reverse annuity mortgages. Some lenders question the legality here of such mortgages.)

The alternative you mention is selling your home, investing the net proceeds in Treasury bonds whose present yield is historically high, and renting an apartment.

Actually, you have another alternative that may be attractive. How about selling your home? You could invest part of the net proceeds (one hopes, a relatively small part) in a mobile home in an attractive subdivision (with such amenities as a clubhouse, swimming pool, tennis courts, etc.) in the Sun Belt.

There are other alternatives. But I'm sure you see my point. It seems to me you really seek personal satisfacton and comfort with an assurance (insofar as possible) that you will always have ample funds to sustain yourself in the manner you desire. How you arrange your life in your older age is a highly personal decision.

So, look at your problem in that light. If you want to remain in your present home and can afford it, that's preferable. If you want to sell your present home and move into a renatal apartment and can afford it, that's preferable. If you want Sun Belt living and can afford it, perhaps the alternative I've outlined is preferable.

Q: I live in a condominium building that was recently reassessed for real estate taxes. The assessed valuation and the taxes increased 80 percent. rNeedless to say, all of the owners were appalled. We are unsure of the direction to take. Could you please advise?

A: Examine the document that notified you of the increase (or proposed increase) in your assessed valuation. There is normally an opportunity to appeal within a specified time. Examine the records in the assessor's office to determine the basis for the increased assessment valuation. After doing this, and consulting with your fellow condo owners, you can decide how best to present your case. At that point, you can also decide whether you need to retain an attorney to represent you or whether you (all the condo owners) can handle it yourselves. Don't delay.