Long Term Government Bonds

We study the impact of debt maturity on optimal fiscal policy by focusing on the case where the government issues a bond of maturity N > 1: Isolating these effects helps provide insight into the construction of optimal government debt portfolios. We find long bonds may not complete the market even in the absence of uncertainty, generate an incentive to twist interest rates and induce additional tax volatility compared to short term bonds. By focusing just on the issuance of long bonds we show that as well as their well known advantage in providing fiscal insurance long bonds also have less attractive features that induce additional tax volatility. In the case of long bonds, governments induce tax volatility in order to twist interest rates at maturity. This interest rate twisting effect is what makes optimal debt management models so difficult to solve computationally as the state space rapidly becomes cumbersome due to the need to keep track of promises about future tax rates. We provide an alternative institutional setup (\independent powers\) that eliminates this problem offering a simpler solution method. Introducing maturity requires making more institutional assumptions than is the case for one period bonds. In particular assumptions have to be made whether the government does or doesn't buy back each period all outstanding debt irrespective of maturity and whether long bonds pay coupons. This is important as the literature to date makes assumptions that are diametrically opposite to what is observed in practice. We show that this is an important divide as if we model optimal policy under the empirically motivated assumption that governments do not buyback bonds until maturity then long bonds induce additional tax volatility due to the existence of N period roll over cycles. These can be reduced in magnitude by the government issuing long bonds that pay coupons although because coupons reduce the duration of a bond below its maturity this does compromise the ability of long bonds to provide fiscal insurance.