Roth 403(b) to Roth IRA?

Hi all,

I am 25, living in the US, and just starting grad school. One of the benefits I am offered is a 403(b) retirement plan. The annual contribution limit is around $20,000 with relatively negligible fees.

My understanding is that the 403(b) can be set up as a Roth (after tax) account. This would allow me to roll over up to $40,000 to my Roth IRA once I finish my graduate program in 2 years and am no longer employed by the university.

Am I missing something or is this an easy way to contribute more than the annual limit of $6500 to my Roth IRA? I would appreciate any thoughts, especially from anyone with experience with this type of rollover.