(2)No registered dealers shall collect from any person any such amount except in a case in which, and -to the extent to which, such dealer is liable to pay tax under this Act:Provided that where a registered dealer is in doubt about his liability, he may collect and keep in deposit the tax so collected towards his anticipated liability of tax; but shall refund the deposit to the person from whom it was collected or to his successors or assignees, if any, to the extent up to which it is finally determined in the proceedings under this Act, that the dealer is held not so liable.
