Q. In 1971, I bought a home that has increased significantly in value. I purchased the home in my own name, and although I have married since, the deed is still in my name only. My husband and I have lived in the house together since 1973. I am 46 and he is 56. Do we qualify for the once-in-a-lifetime "senior citizen" exemption if we sell the house? If not, and if we have a new deed drawn up listing both names, must we wait for three years before we can take advantage of this tax deduction?

A. I find it interesting to be discussing the so-called "senior citizen" exemption for people who are still quite youthful.

This once-in-a-lifetime exemption permits taxpayers to exclude up to $125,000 of profit in their personal residence if certain conditions are met. These conditions include:The taxpayer must be at least 55 years old before the date of sale. The exclusion applies only to the sale of the principal residence, although this may include condominium and cooperative apartments. The taxpayer must have owned and used the property as his or her principal residence for a total of at least three years during the five-year period ending on the date of the sale.

For married taxpayers filing separate returns, the maximum exclusion is $62,500 on each return. If one spouse meets all three requirements for the exclusion, both spouses are treated as meeting the requirements.

Thus, if your husband -- who is over 55 -- qualifies, the fact that you have not yet reached that age does not disqualify the exemption.

Although the tax law is not always clear, the Internal Revenue Service has given some guidance on the specific question you have raised. According to the IRS, qualifying ownership and use need not be concurrent. Take, for example, a case where a taxpayer occupied a rental apartment that later was converted to a condominium unit, which the taxpayer purchased. According to the IRS, the use requirement has been met because of the length of time the taxpayer occupied the property, even though he or she did not own it the whole time.

Thus, in your example, because you and your husband have lived together in the house since 1973, once your husband takes ownership of the property, I believe you will be able to qualify for the once-in-a-lifetime $125,000 exemption.

To qualify, you should deed the property into both of your names. I am assuming that you do not file separate returns, for that would defeat your opportunity to take the full $125,000 deduction.

However, there may be tax considerations if you do transfer the property into both of your names, and before you take this step, I strongly suggest that you consult your own tax adviser.

You also should consider seriously whether this is the time to take the exemption. If you are planning to purchase a new house whose value is equal to or greater than the value of your current house, you still can exclude much of the profit for tax purposes, without resorting to the senior-citizen exemption, by rolling the profit over into the cost of the next home. This would let you defer any tax on profit until you sell your last house. If, for example, you are moving to an area with potential growth and where houses may be appreciating significantly, perhaps you should wait to take the senior-citizen exemption until you sell that next house. Remember, this is a once-in-a-lifetime exemption, and you should plan carefully now to preserve all of your options.

Tax planning should play a significant role in all our lives. I am pleased that you are taking an active interest in this planning process now. Unfortunately, too many of us wait until it is too late.