The inquiry was launched following controversy over Plan 2 loans, which were issued in England between September 2012 and July 2023 and are still issued in Wales.
Graduates with Plan 2 loans have been paying back 9% of everything they earn over the repayment threshold which currently stands at £28,470.
This threshold will remain frozen at £29,385 from 2027 to 2030, rather than rising with inflation.
That means graduates will effectively start repaying sooner and those earning above the threshold will see a greater proportion of their salary subjected to student loan repayments than they would have done.
In April, after the inquiry was launched, the government said interest on some student loans in England will be capped at 6% in the next academic year to protect graduates from the risk of rising inflation due to the Iran war.
Campaigners have welcomed this but called for wider reforms to the system.
Alex Stanley, vice-president of the National Union of Students, said the data showed “how damning the situation is”.
“Students and graduates already knew this was the case, because we are living it. Governments have repeatedly changed the terms, in a move that no bank could do, making the conditions worse while we have no option but to take the financial hit”.
