You should seek advice on this

Please seek further advice on this. Things may vary depending on your situation.

Here is an excerpt from a 2003 Issue Paper on this :

In the Supplemental Security Income (SSI) program, for example, two recipients married to each other receive a benefit that is one-quarter less than if they simply lived together but not as husband and wife.

http://www.ssa.gov/policy/docs/issuepapers/ip2003-01.pdf