Scenario
User is creating new tax rate rule with two tax rates in SuiteTax account and receives a notice: A HSN or SAC code can only have one GST rate in the same effective period.
Solution
GST is exempted in case of Sale to SEZ. A HSN code which is used in case of local sale, is also used in case of sale to SEZ. However, users are not able to define GST Tax Rate rule of Sale to SEZ against the same HSN Code which is used in local sale.
As a workaround, users may create two tax rates with the same setup and put some identifier for transaction purposes.