Parity Debt
Two or more issues of bonds with the same priority of claim or lien on the same underlying security and sources of repayment (i.e., revenues) for all of the bonds.
Additional Bonds and the related “Additional Bonds test” are concepts often found in a Master Indenture, Bond Resolution/Ordinance and related documentation. Additional Bonds are Bonds which may be issued in the future under the same Master Indenture, Bond Resolution/Ordinance, and related documentation upon meeting certain conditions designed to ensure that the revenues available to repay the original Bonds, any currently outstanding Additional Bonds, and the proposed Additional Bonds will be sufficient (the “Additional Bonds test”).
Two or more issues of bonds with the same priority of claim or lien on the same underlying security and sources of repayment (i.e., revenues) for all of the bonds.

Rule outlined in Section 147(b) of the code that states private activity bonds are not tax-exempt bonds if the weighted average maturity of the bond issue exceeds 120% of the average reasonably expected economic useful life of the facilities financed with the bond proceeds.