Your return may be subject to the PATH Act
The Protecting Americans from Tax Hikes (PATH) Act is a law that was passed in 2015 that requires the IRS to hold tax refunds that include Earned Income Tax Credit (EITC) and Additional Child Tax Credit (ACTC) until February 15, 2018.
The intention of this law is to help detect and prevent tax fraud. It also give the IRS more time to make sure taxpayers are claiming credits property so that the proper refunds are issued.
See link below that explains more about the (PATH) Act:
PATH ACT