This could affect almost 27,000 retired doctors who have already chosen voluntary erasure or have yet to decide whether to let their registration lapse.
Twelve thousand have already taken their names off the GMC register, and 15,000 more may follow suit. Only 3,000 have decided to stay on.
The GMC will start charging doctors over 65 from 1 January 2009. But following retired doctors' protests it will no longer force them to undergo licensing or take part in revalidation.
'Representations from some retired doctors suggest a more flexible approach,' the GMC said. This will allow retired doctors to write medical reports and undertake similar work.
Registration costs: 27,000 retired doctors may let registration lapse rather than pay a fee.