If you start your retirement planning early, you can include tax-free bonds in your portfolio. However, retirees should note a few things before investing in tax-free bonds. First, they are long-term investments that mature in 10, 15 or 20 years. Invest in tax-free bonds only if you are sure that you will not require the funds for such a long period. Second, as the name suggests, the interest is tax-free, therefore there is no Tax Deducted at Source (TDS) applicable.