Data from the Department for Work and Pensions shows 134,044 households have had support capped by the government, with single females with at least one dependent child accounting for 85% (114,337).
After being reduced from £26,000 in 2016, the latest limits are £20,000 a year per household, or £23,000 in Greater London.
The figures show a far greater number of people being hit by the cap than previously thought.
In March the government won a landmark case when a High Court decision that the cap should not apply to single parents with a child under two was overturned by the Court of Appeal.
“Labour will build a social security system that is there for any of us in our time of need.”
The DWP has been contacted for comment.