Sources and verification
The primary government references behind the figures, formulas and limitations on this site.
Last checked · Published by Cornelia Cove LLC
Each entry explains what was checked. All sources below were checked on Oct 14, 2026. “Checked” records this site’s verification date, not a government publication date. These are public references; the calculator does not read your benefit record.
Figures, timing and calculation rules
- SSA: COLA information for 2027
Confirms the official 3.6% increase, January 2027 Social Security payment timing, and availability of individual benefit notices in December.
Last checked: .
- SSA: latest COLA calculation
Verifies all six July–September CPI-W inputs for 2025 and 2026, the Q3 averages of 317.265 and 328.746, and rounding the percentage increase to the nearest 0.1%.
Last checked: .
- SSA: monthly CPI-W table
Cross-checks the six monthly CPI-W observations against SSA’s longer historical table of BLS data.
Last checked: .
- BLS: CPI-W series CWUR0000SA0
The official BLS data series for the national (U.S. city average) all-items CPI-W, not seasonally adjusted. It is the series SSA uses; the July–September 2025 and 2026 values match SSA’s published calculation.
Last checked: .
- SSA: historical COLA series
Verifies the 1.6%, 1.3%, 5.9%, 8.7%, 3.2%, 2.5% and 2.8% adjustments received in January 2020–2026. SSA’s year column is the year of the December in which each COLA took effect.
Last checked: .
- SSA: COLA determination summary
Dates the 3.6% determination to October 14, 2026, and states that the next COLA announcement is planned for October 2027. The site does not assert an SSA announcement time.
Last checked: .
- BLS: CPI release schedule
Supports checking the September CPI release in October. The calendar changes over time; it is a schedule, not proof of an SSA announcement time.
Last checked: .
- CMS: 2026 Medicare premiums and deductibles
Verifies the $202.90 standard monthly Part B premium for 2026, income-related premium adjustments, and the announcement date of November 14, 2025.
Last checked: .
- CMS: 2025 Medicare premiums and deductibles
Verifies November 8, 2024 as a second example of a fall premium announcement. It does not establish a fixed announcement date for future years.
Last checked: .
- Medicare.gov: current Medicare costs
At this check, the page lists 2026 Part B costs, not an official 2027 standard premium. Also supports the warning that Part D premiums vary and higher-income beneficiaries may pay more.
Last checked: .
- SSA: applying a COLA to a retirement benefit
Explains that the COLA is applied to the primary insurance amount (PIA), with dime truncation and subsequent retirement adjustments, offsets and final whole-dollar truncation. This is why our gross-benefit shortcut is only an estimate.
Last checked: .
- SSA POMS RS 00601.020: rounding of benefits
Section D documents lower-dollar rounding for monthly benefits; section A describes lower-dime rounding in underlying benefit calculations.
Last checked: .
- Social Security Act section 1839(f)
The statutory basis for limiting certain Part B premium increases when they would reduce a qualifying beneficiary’s payment. The protection is conditional, not universal.
Last checked: .
- SSA POMS HI 01001.004: hold harmless
Explains variable Part B premiums and the exclusions for income-related premiums and state Medicaid premium payments. The calculator does not determine eligibility for this protection.
Last checked: .
- SSA: understanding SSI benefits
Supports the SSI limitation: payments depend on income, living arrangements and possible state supplements. The calculator does not compute an SSI entitlement.
Last checked: .
- IRS: Form W-4V, voluntary withholding
Confirms that federal income tax can be withheld from Social Security benefits. This calculator does not calculate or subtract tax withholding.
Last checked: .
2027 Part B: unresolved at this check
No published CMS announcement of the 2027 standard Part B premium was found during this review. Medicare.gov’s current cost table still displayed 2026 amounts. We therefore leave the 2027 premium unverified and identify $202.90 only as a starting assumption carried forward from 2026. A projection or a Medicare Advantage or Part D announcement is not a confirmed standard Part B premium.
How to use these references
Start with SSA’s latest calculation for the COLA and CMS’s annual fact sheet for the standard Part B premium. Then read the rounding and hold-harmless references before comparing this simplified result with an individual payment. If a source changes or a link fails, send the publisher a correction.