Martin Lewis has issued an urgent warning about a cut in Universal Credit that could see hundreds of thousands of people worse off in two weeks' time.
The fear surrounds the little-known 'Minimum Income Floor' - which affects about 450,000 self-employed Universal Credit claimants.
This was suspended for eight months due to Covid-19, but as things stand will be re-instated on November 13.
Martin Tweeted: "On 13 November, there's a huge sink hole awaiting many self-employed as Rishi Sunak's Covid suspension of the Universal Credit minimum income floor ends.
"I.e self employed will be assumed to have earnings for Universal Credit calculation even if they don't.
"I'd suggest self-employed contact their MP asap"
The minimum income floor was designed to stop taxpayers propping businesses that make a loss.
Normally, for each £1 of earnings a low-paid worker loses as a result of a drop in pay, they get 63p back through increased Universal Credit payouts.
But the minimum income floor treats self-employed people as though they earn minimum wage no matter how little they make in a month.
The Institute of Fiscal Studies worked out that as many as 450,000 low-income households see their payments cut by an average of £3,200 a year thanks to this policy.
Martin suggested that any self-employed people who could be affected by the forthcoming change should write to their MP as soon as possible.
So far, despite pressure from Labour as well as Martin and the public, the Government has said nothing more than they are "looking at" the exemption.
DWP officials have insisted not every self-employed claimant will be hit by the minimum income floor.
Universal credit director Neil Couling said it only hits those who are defined as "gainfully self-employed" - meaning those who have zero earnings are "likely" to be spared.
He tweeted: "Position on MIF always more nuanced than headlines suggest."
There are also other exemptions - for example, it doesn't apply to firms in their first 12 months.
