National Disaster Tax Relief Act of 2014 - Amends the Internal Revenue Code to provide tax relief for disasters declared in 2012, 2013, and 2014 by:

• extending through 2014 the election to expense qualified disaster expenses (i.e., for removal of debris, demolition, and repair of business-related property);
• increasing the tax deduction for charitable contributions for disaster relief for individual and corporate taxpayers;
• allowing through 2014 the deduction of losses attributable to disasters;
• allowing waivers of requirements relating to mortgage revenue bonds;
• extending through 2014 the additional allowance for depreciation of business property (bonus depreciation);
• allowing an increase through 2015 of the new markets tax credit limitation amount within a federally-declared disaster area;
• permitting the use of tax-exempt retirement plan funds in federally-declared disasters without penalty;
• allowing an additional tax exemption for individuals who are displaced as a result of a federally-declared disaster;
• allowing an exclusion from gross income of imputed income from the cancellation of indebtedness resulting from federally-declared disasters;
• providing a special rule to allow individuals affected by a disaster in 2012, 2013, or 2014 to claim a full earned income tax credit;
• increasing the rehabilitation tax credit for buildings affected by a federally-declared disaster;
• permitting one additional advance refunding of a tax-exempt bond that is outstanding on the date on which a federally-declared disaster occurs;
• allowing the issuance of qualified disaster area recovery bonds;
• allowing an additional allocation of the low-income housing tax credit in 2014 to states affected by a federally-declared disaster occurring in 2012 or 2013;  
• allowing payments of disaster assistance to tax-exempt mutual ditch or irrigation companies without affecting their tax-exempt status;
• allowing an exclusion from gross income for disaster mitigation payments received from state and local governments; and
• allowing a tax deduction for payments to a tax-exempt natural disaster fund.