Average Life
Number of years to the point at which half of the principal of the bond will have been retired, which in turn gives an indication as to how fast the principal is expected to amortize.
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Useful Life
An accounting estimate of the number of years it is likely for an asset to remain in service for the purpose of cost-effective revenue generation. The Internal Revenue Service (IRS) employs Useful Life for various purposes applicable to Tax-Exempt Bonds.
