UKIP's Northern Irish branch has been hit with a £3,500 fine for handing over an inaccurate spending return for the 2016 Northern Ireland Assembly election.
The judgement was made by the Electoral Commission, the independent body tasked with overseeing elections and political finance in the UK.
In the 2017 Northern Ireland Assembly election in March, UKIP ran just a single candidate, Noel Jordan in the East Antrim constituency.
Mr Jordan received 4.2% of the first preference vote and was eliminated at the fourth count.
In its filing, the party said that its collective spending for the election had been zero, with expenditure covered by its candidate's return.
The Electoral Commission ruled some of its spending counted as party spending rather than candidate spending and should have been included in the return.
UKIP Northern Ireland has paid the fine.
Speaking about the ruling, the Electoral Commission's director of political finance and regulation Bob Posner said: "Annual accounts are the only information available to voters providing an overview of a party’s finances. In the case of parties which do not receive donations above the reporting threshold, it is also the only information available to voters as to the party’s income.
"That being the case it is important that these parties deliver accounts, and do so on time. The majority of smaller parties do so and we will take action where others do not."
Mr Posner added that it had made a request to the British government for an increase in the level of fine that can be imposed.
The maximum fine that the Commission can currently impose on a political party sits at £20,000, with fines proportionate to the offences committed.
A number of other cases are currently under investigation, and the Commission publishes its findings on a monthly basis.