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The basics
Entering a desired contribution does not guarantee the full amount reaches the account. Legal limits, eligible compensation, household cash, age, employer match, and income-based IRA rules can all reduce it.
Illustrative numbers
The model’s 2026 rule snapshot
401(k)-style employee deferral$24,500 before catch-up
Total additions, under 50$72,000 (employee + employer)
Total additions, 50–59 and 64+$80,000 with the standard catch-up
Total additions, 60–63$83,250 with the higher catch-up
IRA pool$7,500 before catch-up
HSA$4,400 self-only / $8,750 family
The engine carries indexed limits forward using plan inflation and published rounding behavior. The actual amount can still be lower because of income phaseouts or available compensation and cash.
Calculation transparency
How it works in MoneyWhatIf
- 01
The code snapshot includes 2026 elective-deferral, total-additions, IRA, HSA, and applicable catch-up ceilings by person and account kind.
- 02
Traditional-IRA deductibility and Roth-IRA contribution access are reduced through modeled 2026 MAGI phaseout ranges carried into later years.
- 03
Pre-tax elections are fitted before income tax. After-tax requests are then scaled together when take-home pay cannot cover them; HSA uses its own contribution cap rather than a compensation cap.
- 04
Employer match is added separately; elective-deferral and IRA pools are shared per owner, while the total-additions cap is applied to each matched account.
- 05
The total-additions ceiling is what the employee and the employer may put in together in one year.
A catch-up contribution sits above that ceiling rather than inside it, so the combined figure a person may actually receive rises with age: $72,000 under 50, $80,000 from 50 (and again from 64) with the standard catch-up, and $83,250 across the four years 60 to 63 with the higher one.
Sixty-four is the one age at which the figure goes back down, because the larger catch-up is written for ages 60 to 63 only.
- 06
An employer match can also carry the plan document’s own ceiling — a share of pay or a dollar figure a year — so an arrangement written as “50% of the first 6% of pay” pays the 3% of pay it promises rather than half of every dollar deferred. A dollar ceiling is carried up with plan inflation. The smallest of the rate, that ceiling, and remaining total-additions room is what the employer pays.
- 07
A salary can carry a mandatory defined-benefit pension contribution — a share of that pay or a dollar figure a year. It reduces cash and, when treated as an employer pick-up, federal and state taxable income; it never reduces payroll-tax wages and never counts against the elective-deferral or total-additions ceilings.
Keep in mind
Model limits
Employer-plan nondiscrimination testing, HSA eligibility months, and every special catch-up rule are not fully represented. A plan document’s match ceiling is represented, as a share of pay or a dollar figure a year; its other restrictions are not.
A salary can derive a defined-benefit pension from years of service, a benefit percentage and final average pay, or the benefit can be entered as a separate income stream. A derived pension can stay flat, follow inflation, or receive a fixed annual increase. Fixed increases can be simple (based on the initial benefit) or compound (based on the previous year's benefit); existing plans retain compound increases unless changed. Increases begin in the projected year after the benefit starts, rather than on a pension provider's payment date. An after-tax contribution's recovered basis is not tracked in retirement.
Limits are a 2026 code snapshot projected forward, not future published limits. The age 60–63 higher catch-up is modeled; the 2026 requirement that certain higher-wage workplace catch-ups be Roth is not.
The model constrains saving for planning consistency; it does not determine legal eligibility or correct an excess contribution.
This explanation documents the planning model. It is educational, not individualized tax, legal, Medicare, or investment advice.
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Related financial terms
Plain-English definitions, with 2026 figures and worked examples, from the financial terms glossary.