The Social Security Administration publishes the arithmetic behind Supplemental Security Income in plain subtraction, and one worked example shows how a small state payment fits on top. In SSA’s illustration, a person living alone with a $300 Social Security benefit has a federal SSI payment of $714. A $15 state supplement for an individual living alone brings the combined total to $729.
The subtraction that produces $714
SSI is not a flat check. The 2026 federal benefit rate for an eligible individual is $994 a month, which SSA’s rate table labels as a monthly maximum that took effect in January 2026 after a 2.8 percent cost-of-living adjustment. Income reduces that ceiling.
The SSA page on how unearned income counts runs the numbers for someone whose only income is a $300 Social Security benefit. The first $20 is not counted, which leaves $280 of countable income. Subtracting $280 from $994 leaves a federal SSI benefit of $714. That result is the base figure the supplement then builds on.
Where the $15 comes in, and why it is only an example
In SSA’s Example C, the same $714 is added to a $15 state supplement for an individual living alone, producing $729. The page notes that state supplements vary with living arrangement, and $15 is the figure SSA chose to illustrate the case of a person residing alone.
The $15 is therefore an illustration and not a national amount. No source here sets a standard supplement, and the title of this piece is worded to say so. A state that pays a supplement decides its own figures, and a person living with others or in another setting can see a different amount from the one SSA picked for the example.
Questions about SSI amounts usually come down to the income limits and what has to be reported, and The SSI & Disability Action Kit includes the 2026 SSI income and resource limits and review and reporting steps.
Open the kit’s 2026 SSI income and resource limits →
Which jurisdictions supplement and which do not
SSA’s page on state supplementary payments separates places where SSA itself administers a supplement from places with none. The twelve in the first group are California, Delaware, the District of Columbia, Hawaii, Iowa, Michigan, Montana, Nevada, New Jersey, Pennsylvania, Rhode Island and Vermont.
Seven are listed as paying no supplement at all: Arizona, Arkansas, Mississippi, North Dakota, the Northern Mariana Islands, Tennessee and West Virginia. For a resident of one of those, the federal calculation ends at the federal figure, and the $15 in the example does not apply.
Those lists describe the supplements that SSA’s page identifies. They do not say what any particular state pays, and a state’s amount can differ by living arrangement.
What moves the number up or down
The structure of the formula answers most questions about why two people receive different SSI payments. Every dollar of countable unearned income, after the $20 exclusion, lowers the federal payment dollar for dollar in the example. A higher Social Security benefit would leave less than $714, and no other income would leave the full $994.
The example uses a single figure, a $300 Social Security benefit. SSA’s page works through other combinations, but this one is the case where a state supplement is added. A change in living arrangement, in income or in a state’s rules would change the total, which is why SSA publishes the examples in separate cases instead of one number.
SSA’s page also draws a line between kinds of income. The example here is unearned income, such as a Social Security benefit, where the first $20 is not counted. Earnings are treated differently: the page says the first $65 of earnings and one half of earnings over $65 received in a month are not counted. A person with both kinds of income therefore cannot copy the example arithmetic directly and has to apply each rule to the right income.
Checking a payment against SSA’s own examples
The free source is SSA’s page on how income counts for SSI. A person trying to understand a payment can write down each source of monthly income, subtract the $20 that SSA does not count, and compare the remainder to the $994 federal rate listed on SSA’s 2026 benefit rate table. If a state supplement applies, SSA’s page on supplements shows whether the agency administers it.
When the arithmetic and the amount on a statement do not match, the usual causes are income that changed, a different living arrangement or a state-specific rule. SSA’s worked examples are the reference point for checking the federal side first.
The SSI & Disability Action Kit is a 10-page kit that adds an income and resource organizer to the review and reporting steps, for keeping the monthly figures in one place.
Get The SSI & Disability Action Kit for the income-exclusion rules →
This piece was drafted with AI assistance; the figures and dates were checked against the Social Security Administration pages linked above.
