In the US, there are separate state and federal taxes. The sales tax in California is a state tax, whereas the VAT idea that's being floated would be a federal

In the US, there are separate state and federal taxes. The sales tax in California is a state tax, whereas the VAT idea that's being floated would be a federal tax. That's why adding a VAT in the US would not supplant any existing sales taxes (or state income taxes).