Douglas Carswell, Ukip's only MP, has refused to use £650,000 of taxpayers' money to hire 15 members of staff for his parliamentary office.
Mr Carswell said he was approached by Ukip officials and asked to use the money - known as 'Short money' - that the party is entitled to after he retained his Clacton seat.
But Carswell rejected the suggestion, arguing that it was inappropriate and that he would not be able to "look pensioners in the eye".
He suggested that "not even a US senator would have 15 staff", and that he would claim "less than half" of what Ukip is entitled to.
"They approached me with a proposal to employ 15 people in addition to what I have got," Carswell said.
"I politely and firmly said that's not going to happen. I politely and firmly explained I would be putting forward a sensible proposal that was respectful to the taxpayer and to public sector workers in my constituency who have not had a pay rise for five years.
"I'm not going to allow anyone to create a Ukip trough in the House of Commons."
He added: "Ukip is supposed to be different and Ukip will be different."
The row comes after Nigel Farage performed a U-turn and stayed on as party leader, just days after he resigned following his failure to win his South Thanet seat.
Senior UKIP figures have defended Carswell's stance on Twitter.
What is Short money?
How much 'short money' parties are entitled to for every seat that they win at a General Election.
Short money is a payment given to opposition parties to help them with the costs that they rack up performing their parliamentary duties.
Parties are entitled to £16,689 for every seat that they win at a general election (UKIP won one seat) as well as £33.33 for every 200 votes gained.
The aim is to create more of a level playing field, and the money is often used to help hire extra research staff.
Poll: Is Douglas Carswell right to reject the money?