NHS England expects to confirm later this month whether the 1 October deadline for all patients to have access to extended hours GP services has been met - but board papers published in September said the health service was 'on track to meet this commitment'.
NHS England has estimated that extended access to primary care service will provide an extra 9m appointments per year.
The target for full national rollout of GP extended hours was brought forward to 1 October from 31 March earlier this year, when NHS bosses revealed in February that more than half of the country had access to GP appointments outside core hours.
The £10m winter indemnity scheme for GPs has this year been widened to offer support for doctors taking on extra shifts in extended hours for the first time, in addition to the usual support for out-of-hours or unscheduled care work.
Extended GP services involve providing access to pre-bookable and same-day GP appointments in the evening (after 6.30pm) and at weekends, although these are not necessarily at patients' own practice.
GPC chair Dr Richard Vautrey said: 'This is clear evidence of what GPs can achieve if they are provided with additional recurrent funding.
'This is valuable extra capacity so it's important going forwards that these services can be used flexibly by local practices to support patients struggling to get appointments with their surgeries during the day.'
GP practices faced tighter rules on core hours opening requirements from 2017/18, with practices told they could be stripped of the right to provide the extended access DES - worth around £8,000 to an average practice - if they closed during core hours for training.