Martin Lewis has warned millions of furloughed workers to check their payslips.
The Money Saving Expert says employees could be getting shortchanged by businesses that aren't playing by the book.
It comes as the rules surrounding the safety net that was put in place at the start of lockdown change, with the government reducing its financial support and employers shouldering more of the burden.
Since the beginning of September, the government has been paying 70 percent of wages up to a cap of £2,187.50 for employees who have been furloughed - down from the initial 80 percent.
Bosses are also having to top this up by 10 percent to cover the difference, and pay national insurance and pension contributions, too.
Then, from October, the government's contribution will fall by a further 10 percent, down to 60 percent, with a cap of £1,875 for the hours an employee is furloughed.
However, Martin has now warned workers in his weekly newsletter to make sure they are being paid correctly.
He says: "Since Apr, 9.6m roles have been furloughed - this is where your job's put on standby and you get up to 80 percent of your salary, up to £2,500/mth.
"From this month though, the Govt is only covering 70 percent of salaries and employers are being asked to pay the rest, plus national insurance and pension contributions. Yet you should still get the 80% - do ensure your employer's paying you what you're due.
"Plus if your employer asks you to work, it should be giving you full pay for the hours you do, and you only get furlough pay for the rest of your normal hours that you don't do (if any)."
Martin also advised workers to speak to their employer if they're uncomfortable about returning to work.
Though he pointed out that if proper precautions have been taken and there are no underlying health conditions, it could prove tricky to remain on furlough.
Max Winthrop of the Law Society's Employment Law Committee advised: "If you're healthy, have no special risks through an underlying condition and can travel safely to and from the office, refusing to work is usually difficult, and could lead to a disciplinary, including dismissal."
While Ruby Dinsmore, employment lawyer at Slater and Gordon, said it was important to see if your boss could shift your hours around to help with travel arrangements.
She added: "If, for example, you usually travel by heavily-populated public transport, see if flexible working or travelling out of peak times works for both you and your employer."
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