The pro-Jeremy Corbyn group Momentum has been fined £16,700 for “multiple breaches of electoral law”.
The fines include the highest ever dished out to a non-political party campaigner for failing to declare a complete and accurate spending return, the Electoral Commission said.
It comes eight months after the official Brexit campaign, Vote Leave, was fined £61,000 for overspending by almost half a million pounds in the 2016 EU referendum.
The watchdog found Momentum – which boasted thousands of small cash donations – failed to submit a complete and accurate spending return for the 2017 general election.
For this offence the group was fined £12,150.
Momentum also omitted £22,958.46 of reportable donations from a report to the watchdog – earning the group a separate £2,700 fine.
Yet Momentum today insisted that the Commission found no evidence the group overspent its limit, despite the limit being just £37,920.
Elsewhere Momentum failed to provide the required declaration to accompany a post poll donations report – earning it a £250 fine, the Commission said.
And the group failed to provide all required invoices with their spending return, triggering another £250 fine, the Commission said.
During its investigation the Commission also found Michael Chessum, a Momentum manager, failed to report a £10,000 donation from the TSSA union within 30 days. This incurred a £900 fine.
Mohammed Afridi, another manager, failed to report a separate £8,000 TSSA donation within 30 days – triggering a £450 fine.
Louise Edwards, Director of Regulation at the Electoral Commission, said: “The fines that we have levied reflect Momentum’s repeated revisions to their spending return, poor record keeping and failure to follow advice given by the Commission prior to the election.”
Momentum was set up in 2015 to support Jeremy Corbyn’s leadership of Labour and now has tens of thousands of members.
It later ordered that all members must also be members of the Labour Party, and held multiple rallies across the country to support Mr Corbyn.
Momentum today issued a lengthy statement complaining “the level of detail required under the law was often comic” and insisting “we won’t make these mistakes again”.
Spokeswoman Laura Parker said the Electoral Commission had found the group did not overspend, despite its spending limit being just £37,920.
“We managed to do a lot with very little,” she said, claiming tens of thousands of unpaid volunteers meant the campaign knocked 1.2m doors on election day.
She added: “The Electoral Commission did find some mistakes in our reporting and some clerical errors.
“This isn’t surprising for a new organisation which at the time was less than two years old and had 25,000 members and 150 local groups.”
But she complained Momentum was left in the “absurd” situation of finding year-old spending for the run-up to the surprise, unexpected snap election.
She branded the regulations “gagging laws introduced by the Conservatives” designed to “throttle volunteer-led campaigning organisations”.
She added: “The level of detail required under the law was often comic.
“In one instance, the Electoral Commission queried the purchase of a pizza, wanting to know what percentage of the pizza was eaten by staff members and what percentage by volunteers.”
She branded the level of fines “disproportionate” but said: “We won’t make these mistakes again. In accordance with the wishes of the Electoral Commission, we have put in place comprehensive systems and processes so we can fully adhere to the regulations next time and be ready for an election if it’s called tomorrow.
“Adhering to these regulations is costly, and that’s why we will launch a fundraising drive to pay these harsh fines and to ensure we’re ready to win the next election for Labour.”