IUL vs 401(k) Comparison Calculator

How Indexed Universal Life (IUL) Works

Indexed Universal Life is a permanent life insurance policy where the cash value grows based on a stock market index (typically S&P 500), but with a cap on annual gains and a floor of 0% — meaning you never lose money in a down year. The cash value grows tax-deferred and can be accessed via tax-free policy loans in retirement. The insurance company subtracts cost of insurance (COI), administrative fees, and expense charges from your premiums and cash value annually. Total fees typically run 1.5% to 3.5% per year, much higher than index funds (source: NAIC Indexed Universal Life Buyer's Guide).

How a 401(k) Works

A traditional 401(k) is an employer-sponsored retirement plan where contributions are pre-tax (reducing current taxable income), grow tax-deferred, and are taxed as ordinary income on withdrawal in retirement. 2026 contribution limits: $24,000 for under-50, $31,000 with catch-up. Most 401(k) plans offer index funds with expense ratios of 0.05% to 0.50%. Many employers match contributions — typically 50% match up to 6% of salary — which is essentially a 50% guaranteed return that no IUL can match. Withdrawals before age 59½ generally incur a 10% penalty (source: irs.gov, Publication 575).

The Hidden Cost of IUL Caps and Fees

IUL marketing emphasizes the 0% floor (you can't lose money), but ignores three critical drags on returns. First, the cap: if the S&P 500 returns 25% in a great year, your IUL credits only the cap (typically 9-11%), giving up 14-16% of gain. Over 30 years, this caps-vs-uncapped difference compounds dramatically. Second, dividends are excluded — the S&P 500's historical 10% return includes ~2% dividends, so you're actually compared against a 8% price-only index. Third, annual fees of 2-3% directly reduce your returns. Real-world IUL net returns over 20-30 years typically deliver 4-6% annualized, well below the S&P 500's historical 10% (source: Society of Actuaries 2024 IUL study).

When IUL Might Make Sense

IUL is best suited for high-income earners (>$300K/year) who already max out 401(k), Roth IRA, and HSA, want permanent life insurance, and need additional tax-advantaged growth. The death benefit and tax-free loan access add real value beyond pure investment return. For 95% of Americans, contributing the matched portion of a 401(k), then maxing a Roth IRA, then maxing the rest of the 401(k), then opening a taxable brokerage account in low-cost index funds delivers higher net wealth than an IUL. The CFP Board, Consumer Federation of America, and most independent fiduciary advisors recommend skipping IUL for retirement saving (source: CFA, "Indexed Universal Life Insurance: Consumer Concerns").

IUL vs 401k Comparison — What the SEC and NAIC Say About Illustration Math

If a salesperson hands you an IUL illustration projecting 7–8% annual returns, treat the page like a pitch deck, not a financial plan. Per the SEC Investor Alert on equity-indexed products and the NAIC Life Insurance Center for Insurance Policy & Research, IUL illustrations may use the "Index Account" historical lookback under AG-49, which is the most generous regulatory cap — not a guarantee. The actual cap can be lowered by the insurer at any policy anniversary, the floor of 0% locks you out of upswings after market drops, and the fees compound silently against cash value for 10–20+ years. Run this calculator with three scenarios for honesty: (1) the agent's illustrated 7% return, (2) a 5% mid-case under realistic cap adjustments, and (3) a 4% low-case with 3% annual fees. The gap between scenarios 1 and 3 over 25 years is typically 50–70% of total accumulated wealth — the reason most fiduciary CFPs steer clients to 401(k) + Roth IRA + HSA first.

Last updated 2026-06-14. Sources: SEC Investor Alert, NAIC CIPR — Life Insurance, Consumer Federation of America.