Cash-strapped Sauber have announced they won't take part in Formula One's first in-season test in Barcelona after next week's Spanish Grand Prix.
Sauber cited two main reasons for the decision in an announcement on Twitter - the absence of car updates and the lack of a test driver who meets the requirements.
The 2016 sporting regulations stipulate that teams must allocate at least two of the four in-season test days to young drivers.
Sauber, whose technical director Mark Smith left in March, were the last team to test their 2016 car before the season started and are going through financial difficulties.
They confirmed recently that monthly salaries were paid late in February and March.
The team were also paid an advance, along with two other outfits, on their 2016 revenues from the commercial rights holder at the end of last year to tide them through the European winter months.
Team principal Monisha Kaltenborn was absent from last weekend's Russian Grand Prix.
"We have financial difficulties, it's not a secret. The good thing is that we are still around. We are working hard to solve all the problems but it's not easy," team manager Beat Zehnder told reporters in Sochi.
"An annual budget this year is just a massive one and to just cover it by sponsors and the income from (F1 commercial supremo) Bernie (Ecclestone) is just not sufficient," he added.
Zehnder said exchange rate changes had added to the difficulties, with many sponsorship contracts paid in US dollars or Euros while Sauber's salaries are paid in the 'safe haven' Swiss currency.
"In 2007 one dollar was 1.5 Swiss Francs.
Now we have parity. So whatever we have on income in dollars is now worth less," said Zehnder.
Sauber, who have been in Formula One since 1993, have yet to score a point in four races this season with Sweden's Marcus Ericsson and Brazilian Felipe Nasr.