From 6th April 2017, Child Tax Credits and the child element of Universal Credit will be limited to two children for children born after this date.
Caritas Social Action Network (CSAN) campaigned against this change in policy last year, arguing as part of a coalition of faith groups that all children in low-income households need society's protection, not just the first two.
Families on low-incomes who have a third child this year will receive £2,500 a year on average less than they would have done in previous years. Families with four children will receive on average £7,000 less.
Phil McCarthy, CEO of Caritas Social Action Network (CSAN), said: "Families are key to the health and prosperity of our society. Recent research from CSAN member Marriage Care identified money worries as the leading cause of relationship strain.
It is therefore likely that this policy, which reduces financial support for larger families, will add to the costs that society pays for family breakdown - costs which are more than financial.
We hope that the Government will review the effects of this policy over the coming year, and decide against enforcing it from November 2018 on all claimants, regardless of when their children were born."