Former chancellor George Osborne made more than £320,000 over 31 days for giving speeches, records show.
Mr Osborne declared payments for six speeches between 27 September and 27 October, including to a US bank and a university.
The Tatton MP was sacked by Theresa May when she became prime minister. He is now a backbencher.
His largest fee was £81,174 from JP Morgan for a speech on 4 October, the register of MPs' interests shows.
A total of seven hours' work was listed for this and another speech for which he was paid £60,578 from JP Morgan.
Mr Osborne signed up to the Washington Speakers' Bureau, from where he is due to be paid £80,240 from a company called Palmex Derivatives for a speech in New York he gave on 27 October - which he recorded as a total of two hours' work.
He also expects to be paid £69,992 by the Securities Industry and Financial Markets Association in return for speaking on 27 September and 18 October, and £28,454 from the Hoover Institution at Stanford University for a speech on 17 October, listed as three hours' work.
Under Parliamentary rules, MPs have to register within 28 days any interest which could be seen as influencing their actions or words.
The latest edition of the register also reveals former justice secretary and Conservative leadership candidate Michael Gove expects to be paid £150,000 a year for writing for The Times, which is listed as taking eight hours a week.
He also received a £17,500 advance payment for a book.