When you are creating journal entries or changing an account within the write check window that include a Sales Tax Payable account, QuickBooks will present a warning message stating: "You must specify a vendor name for the sales tax account."
When you are creating journal entries or editing a check that includes the Sales Tax Payable account, QuickBooks requires that you include the tax vendor's name in the Customer:Job column.
You will need to put the Sales Tax Vendor name in the Customer:Job column. For example you might use "City of Tucson" for a local city sales tax vendor name. If that name does not exist in your Vendor name list, QuickBooks will allow you to use the quick add feature to add the vendor.