The number of cases taken to employment tribunals has fallen by 70% since fees were introduced, a 2016 government review has found.
Unions called for the fees of up to £950 to be scrapped, saying the slump in claims mostly affected low-paid women.
The review said the introduction of fees had dramatically changed how workplace disputes were resolved, with a significant increase in the number of people turning to the conciliation service Acas.
The number of multiple claims taken to employment tribunals fell from 5,847 before fees were introduced to 1,740 in the year afterwards (2014-15) – a reduction of 70%. The number of single cases fell by a similar percentage.
The original estimate was a drop of 25%.