The poll tax was illegal when it was introduced into Scotland before the rest of the so called "UK'. Any graduate tax would also be illegal under the terms of the Treaty of Union 1707.

It would also restrict the ability of graduates to leave Scotland or England and move abroad to work. How would they pay this grievous tax if they were working in the USA? There is no reciprocal agreement. The tax would lead to virtual imprisonment of graduates in the "UK and infringe their baisc human right to freedom of choice.