Do you have to do a postgraduate degree at the same university did undergraduate degree?

It is not necessary to do a postgraduate degree at the same university you did your undergraduate degree. You can apply to any university that offers the postgraduate program you are interested in, regardless of where you completed your undergraduate studies. There may be some advantages to staying at the same university for your postgraduate degree, such as being familiar with the campus and having established relationships with faculty and staff. However, there are also advantages to moving to a new university, such as gaining exposure to different perspectives and ideas and building a new network of colleagues. Ultimately, the best decision for you will depend on your individual circumstances and preferences.