Capital improvements made to a principal residence are not tax deductible. Instead, they are added to the basis of the home (usually what you paid for it). This increased basis serves to reduce the amount of gain that results when the home is sold. However, certain energy-related improvement may entitle you to a tax credit now.
A 12-month period ending on the last day of any month other than December. Partnerships, S corporations, and personal service corporations are limited in their choice of fiscal years and face special restrictions.