Both undefeated fighters are said to be keen on the pre-title meeting, although the contest could head to purse bids unless an eleventh-hour deal can be reached in the coming hours.
The pair had originally been informed that the deadline would be near the end of August until their respective promoters, Yvon Michel and Main Events secured a 30-day extension from the IBF.
That runs out imminently as the pair eye a shot at Sergey Kovalev with a victory.
Former amateur Beterbiev, 30, has made a perfect start to life as a pro by stopping all nine of his opponents, whilst 33 year-old Barrera has made steady progress over six years in the paid ranks which currently sees the Cuban boast a C.V of 16 wins and eleven stoppages.
Beterbiev was offered an immediate shot at champion Kovalev earlier this year but opted to wait until after one more fight, which should happen by the end of 2015 once the Russian and Barrera sign the contracts.
Barrera is actually rated number eight with the IBF – but was handed the chance when Erik Skoglund, Andrzej Fonfara, Bernard Hopkins, Sean Monaghan and Jean Pascal all declined the offer to take part.