Red Bull team principal Christian Horner (centre) has strongly defended his teamRed Bull have been found guilty of breaking Formula 1's budget cap by the sport's governing body, the FIA.
Red Bull exceeded the $145m (£114m) limit during 2021, the FIA said, adding that the offence was "minor", the lower of the two categories of breach.
This means the team exceeded the cap by less than 5%, or $7.25m.
Both Red Bull and Aston Martin were also found guilty of a procedural breach of the cap.
The FIA did not reveal the amount by which Red Bull exceeded the cap, how it had done so, or what penalties would be applied. It said it was "currently determining appropriate action".
Both teams have the possibility of appealing against the decision.
A statement added: "With respect to this first year of the application of the financial regulations, the intervention of the FIA cost-cap administration has been limited to reviewing the submissions made by the competitors and that no full formal investigations were launched."
A procedural breach is not an overspend, but rather a failure to fill in forms correctly. Williams were also found guilty of this and fined $25,000 earlier this year.
Potential penalties for a 'minor' breach include: a reprimand; deduction of drivers' and/or constructors' championship points for the season in question; suspension from one or more stages of a competition; limitations on aerodynamic or other testing; and a reduction of the team's cost cap.
Earlier on Monday, Red Bull team principal Christian Horner repeated his belief that the team were under the cap in 2021, a season in which Red Bull driver Max Verstappen won a close championship fight with Mercedes driver Lewis Hamilton in controversial circumstances at the final race of the year.
"We're very confident we're within the cap and within those financial regulations," Horner told BBC Radio 4's Today programme.
"So we've been shocked at the speculation and accusations that have been made by other teams. We wait for the FIA to conclude their process and we wait to see what comes out. Anything other than compliance we'll be extremely surprised at."
In addition to the potential of an appeal, Red Bull also have the opportunity to enter into a 'settlement agreement' with the FIA.
In this scenario, a team accepts its guilt and the FIA imposes a penalty it deems appropriate.
If a settlement agreement cannot be reached, the dispute will go to an adjudication panel of independent judges, who will look at the case and come to the conclusion whether the offence should be penalised.
If the team is still not happy after that, it can take its case to the FIA's international court of appeal.
Aston Martin did not comment, but their position is understood to be that they spent less than the total amount of the budget cap in 2021 and regret their breach, which centred on administrative protocols that reflect what they consider a complex regulatory interpretation.
Ferrari team principal Mattia Binotto said on Sunday that even a so-called 'minor' breach was a significant offence, and detailed the value of an overspend to a team's competitiveness.
Binotto said: "If there is a breach, the penalty has to be significant. Our car has been developed respecting the budget cap and we know how much even a minor breach would have implied in performance.
"$5m is about half a second, $1-2m is 0.1-0.2secs, which can be the difference between second on the grid to pole.
"It is about 2021. And also over the following seasons. I am expecting full transparency and clarity on the discussions they have had."
Mercedes F1 team principal Toto Wolff has also called for transparency about the process that was used to arrive at the assessment of any offence.
