Keir Starmer will release his tax returns in the next 24 hours, HuffPost UK can reveal.
The move comes after it emerged Rishi Sunak earned nearly £5 million in the last three years.
Sunak became the first prime minister since David Cameron to release his tax returns.
They showed that he paid HMRC just over £1 million between 2019 and 2022.
Starmer said in January that he would also disclose how much he earns and the tax he pays.
It is understood he could do so as soon as today, although it may be tomorrow.
Tax returns dating back to Sunak’s time as chancellor show that between 2019/20 and 2021/22, he received £1,006,374 in income, plus £3,760,588 in capital gains - a total of £4,766,962.
On that, he paid income tax and capital gains tax totalling £1,053,060.
A Labour source said: “So while Sunak was jacking up everyone else’s tax, he was paying a tax rate of about 22% on millions of pounds of income.”
Tory chairman Greg Hands last night urged the Labour leader to follow Sunak’s example by releasing his tax returns.
He told Talk TV: “What I am here to say is it’s a very good thing he has published those tax returns and now Keir Starmer - who made the same pledge on January 29th - needs to also publish.”