Tax-free bonds specified - redeemable 10-year bonds with put/call options; registration required to avail the tax benefit. The Central Government specifies tax free bonds (Series XVIII) as secured, redeemable, non cumulative bonds with interest of 8.20% per annum, redeemable after ten years and carrying a put/call option at the end of years five through nine. Issued in a defined denomination and serial range, availability of the tax benefit is conditional on the bondholder registering their name and holding with the issuer.