A credit that may be taken against one's total tax liability for improvements made to certain properties. Credits of up to 20% of the improvements made to historic properties and up to 10% of the improvements made to non-historic properites are available as of this writing. A variety of conditions and limitations apply, including the dollar value of the improvements in relation to the property's basis, the amount of time allowed for the project, certification requirements, passive loss limitations, alternative minimum tax considerations and others.