Does a married couple have to file joint taxes if one is on Social Security and the other is on Disability?

It is possible for some of the social security benefits to become taxable on any individuals income tax return.

Your question about the other being on Disability is not clear because it does not specify what kind.

How much, if any, of your social security benefits are taxable depends on your total income and marital status. Generally, if social security benefits were your only income for 2009, your benefits are not taxable and you probably do not need to file a federal income tax return.

If you received income from other sources, your benefits will not be taxed unless your modified adjusted gross income is more than the base amount for your filing status. Your taxable benefits and modified adjusted gross income are figured in a worksheet in the Form 1040A or Form 1040 Instruction booklet.