Craig Mackinlay, the Conservative candidate for South Thanet in the upcoming general election, has been charged by the CPS over his 2015 election expenses.
In the last general election, Mackinlay beat then Ukip leader Nigel Farage in the Kent constituency – but questions were soon raised regarding alleged overspending.
He, along with two others, have now been charged with offences under the Representation of the People Act 1983.
Nick Vamos, CPS Head of Special Crime, said: "We have concluded there is sufficient evidence and it is in the public interest to authorise charges against three people."
As well as Mackinlay, his electoral agent Nathan Gray and senior Conservative staffer Marion Little have also been charged.
Mackinlay was "shocked" by the charge saying: "My candidature in South Thanet is entirely unaffected and my campaign continues as before. I will not let this decision affect the hard work I do for my constituents and the hard work I hope to do for them after 8th June.
"Our justice system is underpinned by the presumption of innocence and I am confident that I will be acquitted as I have done nothing wrong and acted honestly and properly whilst a candidate in 2015, and as all candidate do, acted upon advice throughout.
"Clearly this is a shocking decision by the CPS, given that I've done nothing wrong and I am confident that this will be made very clear as the matter progresses.
"I am very disappointed with the way this has been handled by the CPS and Kent Police and I must question the timing of this decision given that Kent Police confirmed on 18 April that their file had been sent to the CPS to review and make their decision: why leave this until a few days before the election?"
Conservatives have rebuffed the claims, defending Mackinlay. A Conservative party spokesman said: "The legal authorities have previously cleared Conservative candidates who faced numerous politically motivated and unfounded complaints over the Party's national Battlebus campaigning.
"We continue to believe that this remaining allegation is unfounded. Our candidate has made clear that there was no intention by him or his campaigners to engage in any inappropriate activity. We believe that they have done nothing wrong, and we are confident that this will be proven as the matter progresses.
"The individuals remain innocent unless otherwise proven guilty in a court of law. The press, parties and those on social media should be aware of the provisions of the Contempt of Court Act and the strict liability rules against publishing anything which would prejudice the course of justice.
"There is a broad consensus that election law is fragmented, confused and unclear, with two different sets of legislation, and poor guidance from the Electoral Commission. Conservatives are committed to strengthening electoral law to tackle the real and proven cases of corruption that were exposed in Tower Hamlets in 2015."
The CPS decided against charging dozens of MPs over allegations of electoral fraud after examining files from 14 police forces across the country.
At the time, they said that there was evidence of inaccurate spending returns but this did not "meet the test" for further action.
Reacting to the news, Nigel Farage said: "Am I pleased that somebody has been charged, yes. My only regret is that there aren't quite a lot more of them because I personally believe that the law has been broken wholesale in by-elections and in the general election also in key target seats."
The former Ukip leader went onto say that he expected the seat to be a straight fight between his party and Labour.
All three will be appearing at Westminster Magistrates Court on the 4 July.
Mackinlay is standing for re-election in next week's general election.