A 15 Year Look Back: $100,000 Initial Investment S&P 500 Index vs. Tax-Free IUL Indexed to S&P 500 With 14% Cap and 0% Floor. Bottom Line after 15 years $8,300 Taxable 401(k) income vs. $23,000 Tax-Free Income in the IUL. $150,000 Taxable 401(k) Assets vs. $254,000 Tax-Free Assets in the Tax-Free IUL. During this 15 year look back, the Tax-Free IUL produced more than 4.5 times more after tax income than the 401(k). Video shows how the tax-free IUL works. No downside risk. Gains are locked in annually. Share in market upside up to a 14% cap.