The officially designated pro-Brexit campaign fronted by Boris Johnson and Michael Gove came under fire regarding spending in the 2016 EU referendum.
The legal limit on campaign spending is £7million, as defined under the EU Referendum Act 2015.
The results are not expected to have any major impact on the Brexit trajectory as it stands.
Michael Gove recently said: “If it had been left entirely to me, the Leave campaign would have a slightly different feel.”
And now the credibility of the campaign is in question.
What was the Electoral Commission ruling?
The probe found “significant evidence of joint working” between Vote Leave and another group, BeLeave, resulting in exceeding spending limits by almost £500,000.
Vote Leave is also accused of returning an “incomplete and inaccurate spending report” with about £230,000 incorrect and invoices for another £12,000 missing.
BeLeave founder Darren Grimes has also been fined and referred to police for overspending by more than £665,000 and incorrect spending reports.
Another group, Veterans for Britain, were also found to have inaccurately reported a donation it received from Vote Leave and fined £250.
The commission also stated Vote Leave repeatedly refused to attend interviews or produce requested documents.
When the documents were made available, there were said to be incorrect or incomplete.
Bob Posner, from the Electoral Commission, said: “The Electoral Commission has followed the evidence and conducted a thorough investigation into spending and campaigning carried out by Vote Leave and BeLeave.
“We found substantial evidence that the two groups worked to a common plan, did not declare their joint working and did not adhere to the legal spending limits.
“These are serious breaches of the laws put in place by Parliament to ensure fairness and transparency at elections and referendums.”
He added: “Vote Leave has resisted our investigation from the start, including contesting our right as the statutory regulator to open the investigation.
“It has refused to cooperate, refused our requests to put forward a representative for interview, and forced us to use our legal powers to compel it to provide evidence.
“Nevertheless, the evidence we have found is clear and substantial, and can now be seen in our report.”
Responding to the findings, a Vote Leave spokesman said: “The Electoral Commission’s report contains a number of false accusations and incorrect assertions that are wholly inaccurate and do not stand up to scrutiny.
“It is astonishing that nobody from Vote Leave has been interviewed by the commission in the production of this report, nor indeed at any point in the past two years.
“Yet the commission has interviewed the so-called ‘whistleblowers’ who have no knowledge of how Vote Leave operated and whose credibility has been seriously called into question.”
The spokesman continued: “Vote Leave has provided evidence to the Electoral Commission proving there was no wrongdoing. And yet despite clear evidence of wrongdoing by the Remain campaign, the commission has chosen to ignore this and refused to launch an investigation.
“All this suggests that the supposedly impartial commission is motivated by a political agenda rather than uncovering the facts.
“The commission has failed to follow due process, and in doing so has based its conclusions on unfounded claims and conspiracy theories.
“We will consider the options available to us, but are confident that these findings will be overturned.”
Head of Vote Leave, Matthew Elliot, tweeted earlier: “Having skimmed the EC’s report, they’ve ignored VL’s detailed evidence, so it’s riddled with errors & conclusions completely wrong. We accepted their invitation for an interview in early March. Senior staff also volunteered to be interviewed. They haven’t followed due process.”