Kimi Raikkonen has admitted he is still waiting on some money from Lotus.
"There is some problem," the 2007 world champion is quoted by Germany's sport1.de in Hungary.
The news could have huge implications for the 2014 'silly season', as Lotus is pushing hard to convince the Finn to stay put rather than move to Red Bull.
Team boss Christian Horner, however, said Raikkonen's considerable salary demands would not be a problem at Red Bull.
"That (money) isn't really an element in our decision making," he said.
It could, however, be a serious spanner in the works for Lotus.
Only a few weeks ago, Lotus' Eric Boullier admitted that while payments to Raikkonen had been late, his salary "has been paid" now.
But Raikkonen revealed in Hungary that the latest problems aren't even new.
"This happened last year, now again so it is not ideal," said the 33-year-old.