In general, Family Cap is a practice which denies a family which is on welfare assistance from the government further such assistance after the birth of yet another child.
This "cap" does exist for the Temporary Assistance for Needy Families (TANF) program because the 1996 federal welfare law block grant afforded states the discretion to apply a family cap policy in this regard. Certainly, more states than not have adopted this policy and some states, such as Arkansas, have seen a reduction in births from people on the poverty level.
With respect to Supplemental Security Income (SSI) aid is provided to low-income people who are age 65 or older, blind, or disabled. The determination of whether individual members of families are eligible is based on income or existence of warrants, parole, or probation under the "fugitive felons" provision issued by Congress; however, there are no "caps" based upon the number of people in the family receiving SSI.
Here is an example of a limitation put on SSI benefits because of income:
Living arrangement D is for individuals in facility where the medicaid pays over 50%. A person is only due a check of $50.00 per month. This is because it considered that the individual has all his basic needs met.
Since medicaid pays over half of the expenses, SSI is reduced.