Can tax rules be created for an upgraded tax regime?

Have a customer who migrated from R11 (11.5.10.2) to R12.  They calculate tax for US and Canada.  All the migrated tax codes (tax classfication codes) work fine but they had one tax group.  We know the tax groups will not work on R12 but could a tax rule be setup under the migrated regime (STCC) to handle this scenario.  I set a rule up but it doesn't work so wasn't sure if there was a patch that is needed to allow rule to work on an upgraded regime or if tax rules are only an option if you switch to