Jeremy Corbyn has published his tax return, prompting claims he appears to have left off his extra salary as Labour leader.
The Labour leader took action in response to Chancellor Philip Hammond saying earlier that he would not release his return as it would amount to "demonstration politics".
The return revealed that in the year 2015/16, Mr Corbyn earned £77,019 from all employment, £36,045 from pensions and state benefits, £1,200 from self employment and £78 from interest in banks and building societies.
At the time his salary as a backbench MP was around £67,000 a year.
It is understood that after he became leader on 12 September 2015, he was entitled to draw a leader's salary of an extra £58,000.
Sky Political Correspondent Lewis Goodall says that if he was drawing the leader's salary, the tax return should include around an extra £40,000 that is not listed on the form.
Goodall said: "Where the question mark seems to be is over his new income that he started to receive from the end of September 2015.
"The income is the same as a Cabinet minister would receive, so that takes him up to about £150,000 a year.
"He only became leader of the opposition in late September so that means there should be about £40,000 worth of extra income for the tax year 2015/16.
"For whatever reason, that income does not appear to be on Mr Corbyn's tax return."
The release of Mr Corbyn's tax return follows similar moves last year by former prime minister David Cameron and chancellor George Osborne.
Both Mr Corbyn and shadow chancellor John McDonnell have been pressuring others to do the same.
Labour tonight have said: "This tax return was prepared by a team of accountants who were given all of the information."
Earlier on Sunday, following a challenge from Mr McDonnell to release his return, Mr Hammond told the BBC: "No. I have no intention of doing so.
"Just for the record my tax affairs are all perfectly regular and up to date. But I think this demonstration politics isn't helping the atmosphere in British politics."