The recent narrative regarding Greek debt sustainability has moved from the debt-to-GDP ratio towards the annual debt financing costs (interest payments + maturing debt). According to this analysis, Greece already enjoys very generous terms until 2020 and beyond and will only require small debt reprofiling measures in terms of interest rate payments and debt maturities after 2022. What is needed according to its creditors is for Greece to continue on the reform path, achieve economic growth and commit to credible fiscal measures that will allow it to maintain high primary surpluses close to 3.5% of GDP. Unfortunately that can only be achieved through tough measures on the pension front. «As long as Greece continues on this path, creditors will do their part» as the story goes.

In my view the above story is problematic, mainly because it relies on Greece achieving and maintaining a 3.5% GDP surplus target, a target which I believe is not credible in the long-run. In order to examine the subject from a theoretical point of view, I will use some well known concepts in economics, debt overhang and dynamic inconsistency.

Debt overhang is a concept usually used in corporate finance. It is based on the idea that, as long as the corporate balance sheet carries too much debt (which always takes precedence in payment over stock), stockholders do not have an incentive to contribute new funds in order to fund new investment projects if the proceeds are mainly used to improve the recovery rate of creditors. Balance can only be achieved if creditors ‘share the costs’ through a restructuring of the liability structure of the company balance sheet.

The same applies in the case of Greece. Its own ‘stakeholders’ do not have an incentive to contribute funds (in the form of high taxes or lower pensions/wages) if the increased surpluses will mainly be used to improve and ‘guarantee’ the recovery rate of foreign creditors. Given that Greece has a negative external balance (especially the cyclically-adjusted figure) it is an accounting fact that a primary surplus will involve a deterioration of the Greek private sector net financial assets position. Maintaining a 3.5% surplus target in the indefinite future involves a very large transfer of financial wealth from the Greek private sector to foreign official creditors with only a small part of the (possible) growth dividend staying in Greece. Most corporations would not accept such a bargain unless under threat, something which is more than evident in the Greek case where the Grexit threat has been thrown around for more than 5 years now.

Dynamic inconsistency on the other hand involves the idea that sometimes the solution to a dynamic optimization problem depends on the specific time when the problem is evaluated, which has the effect that a specific action time path is not credible.

A classical example is capital taxes. A fiscal authority might want to commit to low capital taxes in order to achieve large investment and growth. Yet at time t=1 investment has already been made and the temptation is high to increase capital taxes in order to enlarge fiscal revenue.

In a way, the same applies in Greece. In order to achieve debt sustainability, the fiscal authority must commit to a path of large primary surpluses. Yet, given the fact that such surpluses deteriorate the private sector position and the possibility of a negative shock hitting the economy, it is highly likely that Greece will have to lower its surplus (or even run a deficit) at some point in time. When the time of a negative shock comes, the optimal solution for the sovereign is to try and smooth the effects of the shock on the economy, not maintain a target that will only make matters worse.

As a result, especially given the need to maintain the surpluses for a very long time (in order to achieve debt sustainability), such a path is not credible. The fiscal authority will deviate ‘at the first sign of trouble’.

Combining the debt overhang with the dynamic inconsistency argument leads to a clearly unstable equilibrium. Both the sovereign and the Greek private sector (Greek stakeholders) do not have the incentive to commit on a high surplus strategy. Under completely rational behavior they have every reason to not damage their financial position and maintain the best possible growth rate. Any commitment on the high surplus strategy will not be credible but only a ‘temporary deviation’ in order to avoid short-term negative outcomes since the Grexit threat is still considered credible.

In my view, only a path of low future surpluses (accompanied by a large upfront debt restructuring) is a long-term credible strategy. Otherwise, we ‘ll keep on observing the current ‘stop and go’ path, with the Greek government implementing the least possible measures and its creditors using Grexit as stick and the (insufficient) future debt reprofiling as carrot in a repeated game with a non-optimal outcome.