Formula and method
For each modeled year, grow the opening balance at the chosen return and add year-end employee and employer deposits. Employee deferrals, employer matching compensation and combined contributions are capped using 2026 limits. Caps stay fixed in future years; age changes can change catch-up eligibility.
Worked example
With $50,000 initially, $80,000 salary, a 10% employee contribution, and a 50% match on the first 6% of salary, the year-end balance at 0% return is $60,400: $50,000 + $8,000 + $2,400.