DUP North Antrim MP Ian Paisley has been fined £1,300 by the Electoral Commission.
Mr Paisley was sanctioned for accepting money from two councils who took tables at a fundraising dinner for the DUP in Ballymena in September 2017.
Mid and East Antrim and Causeway Coast and Glens councils paid for tables at the event in Tullyglass House Hotel which was addressed by Conservative MP Michael Gove.
The councils said the payments had been made to the hotel for attendance at a business-related event.
However, the commission said councils are not regarded as legally "permissible donors" for political parties.
As public bodies, councils are not permitted to donate to political parties under the terms of the Political Parties Elections and Referendums Act 2000.
Mr Paisley must pay the fine by October 8. He will also return a total of £2,600 to the two councils.
A spokeswoman for Mid and East Antrim Council said councillors agreed to purchase a table, without objection, and members from different parties attended.
She said senior council officers and representatives from the agri-food sector across the borough also attended to "avail of the opportunity to discuss first-hand with the minister (Mr Gove) their issues and concerns in relation to the agri-food sector post-Brexit".
"Council was requested to make payment to The Tullyglass Hotel and did so electronically," she added.
"Mid and East Antrim Borough Council takes its responsibilities in relation to financial prudence and accountability very seriously."
In 2018, Mr Paisley served a 30-day suspension from the House of Commons for failing to declare two holidays paid for by the Sri Lankan government and lobbying on its behalf.
He narrowly avoided facing a by-election after Parliament's first ever recall petition fell short of the number of constituent signatures required to oust him by around 450.
