The tax break that municipal bonds retained in the resolution to the "fiscal cliff" may be short-lived as lawmakers still have to contend with sequestration. President Barack Obama has suggested limiting the tax break at 28% instead of 39.6%, the current top level. "If and when there is a serious attempt to make substantial reforms to the tax code, I think that there's a risk that the tax exemption could be curtailed or eliminated," said Michael Decker, managing director at SIFMA.