Martin Lewis has issued a warning to all students who started university during or after 2012.
It comes after the Government has announced a plan to freeze the student loan repayment threshold - the earnings level at which loans begin to be repaid.
While a "freeze" sounds good, Martin said, what it means in practice is that most graduates will be around £110 worse off each year.
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The current loan repayment threshold is £27,295 and those with student loans will repay 9% of everything earned above that.
Next year, however, the threshold will go up to £28,550 - a 4.6% increase.
Because the majority of people do not repay their student loans in full, paying 9% of anything above the threshold for 30 years, before any remaining debt is wiped, most graduates will be left worse off by the freeze.
An estimated 17% - the highest earners - repay their student loans in full.
So while the threshold is raised, these people will repay less.
Everybody else will lose out on an extra £110 each year, repaying much more than they would have done in total.
Martin said: "The highest earning graduates will gain from this and the low to mid earners will pay more."
The freeze, if implemented, represents a break with the previous policy made by the Government in 2010 and then reiterated in 2017 by former Prime Minister, Theresa May, that the repayment threshold would be uprated annually "in line with the annual average earnings growth".
The change will impact all students and graduates from England and Wales who started university from 2012 and who took out a loan.
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