Labour has suspended seven rebel MPs for six months after voting to scrap the two-child benefit cap.
The SNP has called for an end to the policy, which would prevent almost all parents from claiming Universal Credit or child tax credit for more than two children.
Ex-shadow Chancellor John McDonnell was among the politicians that backed the policy alongside, Richard Burgon, Ian Byrne, Rebecca Long-Bailey, Imran Hussain, Apsana Begum and Zarah Sultana.
The politicians have now lost the whip meaning they do not count as Labour MPs for the next six months.
Nealy all of the rebels were allies of the former Labour leader Jeremy Corbyn, who backed the SNP motion.
The SNP amendment was rejected by 363 votes to 103.
A series of social media statement were made by the suspended MP's expressing their disappointment of the suspension and reasoning for supporting the motion.
Ms Sultana stated that she would "always stand up for the most vulnerable in our society", and that scrapping the cap "would lift 33,000 children out of poverty."
Ms Begum also said she had voted against the cap because it had "contributed to rising and deepening levels of child poverty and food insecurity for many East End families".
Before the vote, Mr McDonnell said: I don't like voting for other parties' amendments, but I'm following Keir Starmer's example as he said put country before party."
As the new government face their first major test, the decision to remove the whip shows that rebellion will not be tolerated under a Labour government.