5,000 lone parents will lose their One Family payment from today.
By July next year almost 60,000 families will have lost the One Family payment when their youngest child turns 7.
Advocates groups are calling on the Social Protection Minister not to proceed with the cuts.
A spokesperson for Single Parents Acting Together, Leah Speight, said the move will force parents to give up work.
"Particularly for working parents, that will mean … the one-parent family payment, as it's set up compared to jobseekers' [allowance], allows you to work part-time.
"These cuts don't make any sense. You're going to see women in particular giving up their part-time job, so it's just creating a poverty trap."