A round of applause for Theresa Bandell, director of the Baltimore accounting firm Stegman & Co., for answering these readers' questions:

Q. A couple bought a house 40 years ago for $30,000. He died 10 years after buying the house and the fair market value was $70,000 at that time. She sold the house in 2008 for $400,000. What is her basis in the house without regards to improvements or settlement fees? I was told that it is $50,000: one half the fair market value at the time of purchase plus half of the market value at the time of her husband’s death. Is that correct?

A. The wife may be entitled to a full-step up in basis as of the date of death if the house was a pre-77 spousal joint interest, and the wife did not contribute toward the purchase of the property. In this situation the property was purchased in 1969; therefore the wife is entitled to basis of $70,000 as long as she did not contribute money to the purchase of the property.

Q. We are homeowners who will be non-occupying co-borrowers for a house our son will purchase and be on the title. It will be his primary residence. He will be paying a portion of the mortgage and we will be paying the rest (25 him /75% us). We are pretty sure he will be eligible for the first time homebuyer’s tax credit, but if we rent out a room in the same house to help make our portion of the mortgage payment, will this disqualify him from getting the tax credit? Many thanks for any help you can provide on this!

A. Your son will qualify for the credit based on the percentage he purchased and paid 25%. The fact that you are renting your portion of the property does not affect his credit.

Q. My boyfriend and I purchased a house in Pennsylvania in August 2008. I am a first-time homebuyer; he has owned a house before but not in the last 6 years. We are not living in it yet, as we are living in a rental apartment in New Jersey during renovation work. Do we qualify for the first-time homebuyer credit?

A. You both may be entitled to the credit allocated between the two of you, but you must take possession and occupy the property as your principal residence by December 1, 2009.

UPDATE: Got more questions about the $8,000 first-time homebuyer credit? E-mail them to Eileen.ambrose@baltsun.com before Tuesday, Sept. 8, 2009 and then tune in at noon on Sept. 8 for her live chat with IRS spokesman Jim Dupree to get the answers.