Three Formula One drivers have paid up for their mandatory racing super-licences despite a row between the drivers' union and the governing body over the fees demanded.
The International Automobile Federation has confirmed the payments but has not given names it details.
There could be as few as 18 drivers this season if the Honda team is not rescued before the first race in Australia on March 29.
The Grand Prix Drivers' Association has advised drivers to delay signing super-licences pending talks.
The association effectively represents all drivers on the grid despite some, like McLaren's world champion Lewis Hamilton, not being members.
The row goes back to last year when the FIA raised the cost of a licence by more than 8000 euros to 10,000 euros.