if your mother has died, the "cost" you use is fair market value on the date of her death. Add capital selling costs and the cost of subsequent improvements. You must figure the total yourself. Turbotax provides no lines or boxes to enter these details. the is reported as a sale of a capital asset - Schedule D and the results should appear on line 4 of the 1041
if she is still alive, it raises the issue of whether or not the trust should be treated as a grantor trust. if so, the sale is reported on her 1040 (you use actual costs and selling expenses). Use the home sale worksheet since she would likely be entitled to the home sale exclusion. Despite being titled irrevocable, the IRS doesn't care. It's the provision of the trust in place while she is alive that matters. In this situation, ask the lawyer who drew up the trust document.
