Unfounded fears of career reprisals or a move interstate may cost some junior doctors their share of a $31 million unpaid overtime settlement, one lawyers says.

Of the 2700 potentially eligible doctors employed in the ACT over the last eight years, about 1500 have registered for unpaid, unrostered overtime compensation. 

Their payouts potentially range from a few thousand to several tens of thousands of dollars depending on their role in the health system at the time.

But they only have until Wednesday 27 November to register to receive their portion of the payout.