- What is the difference between an ordinary annuity and an annuity-due?
- An ordinary annuity has payments at the end of each period (most loans, mortgages). An annuity-due has payments at the beginning (rent, insurance premiums). Annuity-due has a slightly higher present value because each payment is discounted one fewer period.
- Can I use this for retirement planning?
- Yes — enter your target monthly income, expected rate of return, and years in retirement to find the lump sum needed to purchase that income stream. For variable returns, use Monte Carlo simulation tools instead.
- What discount rate should I use?
- Use your expected investment return for savings calculations, or the insurer's quoted rate for purchased annuities. The rate has a large impact on results — even a 1% difference changes present value by 10-15% over 20 years.