"Combined tax" refers to the combination of contributions and State Unemployment Insurance Tax. This is the total tax paid by the employers on a quarterly basis.
Beginning January 1, 1996, payments for unemployment insurance made by most employers were divided into two parts. The bigger part is referred to as "contributions". This amount is forwarded to the U.S. Treasury for deposit in the state’s account of the Unemployment Trust Fund. This money is for payment of benefits only.
State Unemployment Insurance Tax
The smaller part (up to 20%) is called "State Unemployment Insurance Tax" - (SUIT) and is deposited and held in the state treasury. This principal of this SUIT is to be used only for benefits. The interest earned on the SUIT fund is used to fund the state’s Worker Training Program.