Bonus Depreciation Extension Act of 2014 - Amends the Internal Revenue Code to extend: (1) through 2015, the additional 50% depreciation allowance (bonus depreciation) for business property (through 2016, for property having longer production periods and for transportation property); and (2) the election to increase the alternative minimum tax (AMT) credit in lieu of bonus depreciation by extending to January 1, 2016, the placed-in-service requirement for property eligible for such election (January 1, 2017, for property having longer production periods and for transportation property).