On September 12, 2012, the Internal Revenue Service (IRS) issued final regulations (the Final Regulations) which make it easier to issue fungible tack-on debt instruments in situations where either the original debt instruments or the tack-on debt instruments are issued with original issue discount (OID) for tax purposes. The Final Regulations achieve this result by expanding the definitions of “qualified reopening” and “publicly traded,” both of which are central to the analysis of whether a tack-on debt issuance will be treated as fungible with an outstanding series of debt instruments for tax purposes. The revised definition of “qualified reopening” applies to reopenings on or after September 13, 2012, while the revised definition of “publicly traded” applies to debt instruments issued on or after November 13, 2012.