Hazardous Duty Incentive Pay (HDIP) is considered an incentive pay that is taxable income unless you are serving in a designated tax free zone, such as a combat zone. There is no separate tax credit for special and incentive pays.
For further information on HDIP and other special and incentive pays, please see the following information on the DFAS website: https://www.dfas.mil/militarymembers/payentitlements/specialpay.html