Methodology & Calculator Assumptions

COLA: third-quarter CPI-W

Use BLS series CWUR0000SA0, not seasonally adjusted. Average July, August and September, round the quarter average to 0.001, compare with the highest prior complete third-quarter average, and round positive growth to one decimal percent. Partial-quarter averages are projections and cannot predict the missing month. The 2028 value is a carry-forward planning assumption.

Payment calendars

SSI is scheduled on the first; the pre-May-1997 and dual-benefit Social Security group on the third. Other retirement groups use the second, third or fourth Wednesday according to the beneficiary’s birthday group. Move a payment falling on a national federal holiday or weekend to the preceding business day. Early bank deposit policies can differ.

Medicare and IRMAA

Official 2024–2026 amounts come from CMS. Part A/B planning projections for 2027–2028 and Part D projections for 2028 come from the 2026 Trustees Report. The 2027 Part D base benchmark is official at $41.33 (July 28, 2026), with a $700 deductible and $2,400 drug-spending cap (April 6, 2026, Table V-2). Future IRMAA thresholds use an explicit 3% annual inflation assumption rounded to $1,000; surcharges scale with the respective base premium. These brackets are not announced CMS amounts.

PIA and claiming age

The earnings option uses floor(average indexed annual earnings / 12) and 2026 bend points. It is an approximation for a newly eligible worker, not a lifetime record calculation for an older birth cohort. For a personal comparison use a current PIA from SSA. PIA truncates to the lower dime; payments to the lower dollar. Early and delayed adjustments use SSA monthly factors.

Taxation and earnings withholding

Taxable-benefits results use the ordinary IRS provisional-income formula for single and joint filers, excluding special worksheets. Earnings withholding is the annual aggregate under SSA’s $1-for-$2 or $1-for-$3 rule. Actual whole-check withholding, first-year monthly exceptions, and later benefit recomputation are not modeled.

Savings and retirement timing

Real returns are after inflation and before fees and tax. Convert an annual real return to a monthly compound rate. Income begins at each chosen age; spending occurs at month-end. Savings longevity simulates up to 100 years. Required capital is the maximum discounted cumulative cash shortfall, so a later surplus cannot fund an earlier gap by borrowing.

Pensions and required distributions

FERS uses OPM’s selected gross annuity formula, including the selected MRA+10 age reduction. Military pay covers regular active-duty High-3 and BRS only. RMD uses the original-owner IRS Uniform Lifetime Table and excludes inherited accounts and the younger-spouse table. These estimates do not establish eligibility.