Twin Deficits and Sustainability Of Budget Deficits – Part 1

I am now using Friday’s blog space to provide draft versions of the Modern Monetary Theory textbook that I am writing with my colleague and friend Randy Wray. We expect to publish the text sometime early in 2014. Comments are always welcome. Remember this is a textbook aimed at undergraduate students and so the writing will be different from my usual blog free-for-all. Note also that the text I post is just the work I am doing by way of the first draft so the material posted will not represent the complete text. Further it will change once the two of us have edited it.

Today I am writing about Section 25.2.

Chapter 25 Recent Policy Debates

In this Chapter we consider the following policy debates:

  • 25.1: Ageing, Social Security, and the Intergenerational Debate
  • 25.2: Twin Deficits and Sustainability Of Budget Deficits
  • 25.3: Fixed Versus Flexible Exchange Rates: Optimal Currency Areas, the Bancor, or Floating Rates?
  • 25.4: Economic Growth: Demand or Supply Constrained?
  • 25.5: Environmental Sustainability and Economic Growth

25.2 The twin deficits hypothesis

In Chapter 21, we considered the current account. At its most basic, the twin deficits hypothesis says that there is a relationship between the budget balance and the current account balance.

A common view held by economists is that an increasing current account deficit indicates that a nation is “living beyond its means” – with excessive domestic demand boosting imports and fuelling inflation, which undermines the competitiveness of the nation and restricts exports.

They point to the fact that the current account deficit is a measure of the nation’s overseas borrowing. So for each quarter that the economy is in external deficit, its stock of foreign liabilities increase. These liabilities can be in the form of debt or equity participation in local firms.

Following this logic, an increasing current account deficit indicates that local consumption and investment is becoming increasingly dependent on the whims of foreign lenders.

They also argue that there is a strong and direct relationship between the national economy’s current account balance and its government budget balance and can become twinned” – that is, move together dollar-for-dollar. This is the twin deficit hypothesis.

The hypothesis is based on national accounting relationships that can be used to show that a current account deficit measures the difference between total domestic (public and private) saving and investment.

This viewpoint considers “national” saving to be the sum of private saving and budget surpluses and total investment to be the sum of private and public capital formation. Accordingly, if the budget moves into deficit, they consider national saving to have fallen and/or national investment to have risen, depending on whether the rise in the deficit is driven by public consumption or investment spending.

Accordingly, other things equal, an increase in the budget deficit will result in a rise in the current account account deficit

Further, if the nation has an increasing budget deficit, it is to be increasingly dependent on the foreign purchases of its debt to supplement domestic savers’ purchases of government debt.

So both a rising budget deficit and rising current account deficit indicate an increased reliance on foreign debt purchases, which according to this viewpoint renders the domestic economy vulnerable to unexpected and sudden changes in economic fortunes. Proponents of this viewpoint suggest that the risk of the nation being unable to generate sufficient reserves to pay back the foreign debt rises the longer these deficits occur.

Ultimately, the nation would be forced to default on its foreign debt obligations with severe consequences – such as, the inability to raise capital (private or public) in global markets.

It is argued that the most obvious way out of this risk environment is to restrict government spending and run restrictive monetary
policy (higher interest rates) to encourage increased capital flows even as this strategy reduces the need for them.

The consequences of the imposition of policy austerity are negative – falling real GDP growth and rising unemployment – which suggests that governments should avoid the twin deficits problem in the first place.

Added to the case against deficits, is the claim that they drive interest rates up (through competition for limited loanable funds) and generate inflation (excess demand). High interest rates, in turn, are argued to squeeze out productive investment, making the nation less competitive internationally. This hinders improvement in the trade balance, and competitiveness is further hurt by inflation.

The twin deficits hypothesis thus relies on a direct link between budget deficits and current account deficits, which is considered to lead to undesirable consequences.

What is the validity of these claims?

As we will see there are a number of conceptual and empirical difficulties with the view outlined above. We will see that the “twin deficits” hypothesis is based on a particular causality – budget deficits to external deficits – which may be reversed in reality.

Further, the hypothesis relies on crucial assumptions being made about the private domestic spending and saving patterns, which have rarely held in practice.

Finally, the crowding out component of the hypothesis, where budget deficits drive up interest rates and inflation and reduce export competitiveness is demonstrablty false.

We will show in this section that a currency-issuing government that floats its currency has more domestic policy space to work within that is reflected in the twin deficits hypothesis. We will show that the government can make use of this space to pursue economic growth and increased living standards even if this means expansion of the current account deficit and depreciation of the currency.

We will also demonstrate that the state of the external sector has very little bearing on what we might consider to be a sustainable fiscal stance.

Finally, it is ironic that many economists who advance the twin deficits relationship as a constraint on public spending also claim that deficit spending is not effective in stimulating national income. The two claims are internally inconsistent.

The link between the deficits

In Chapter 5 we developed the sectoral balances view of the national accounts, which showed us that national income movements ensure that there is a unique relationship between the spending and income balances of the government, external and private domestic sectors.

This framework can be used to demonstrate the accounting basics of twin deficits hypothesis. At the macroeconomic level, the final expenditure components of aggregate demand are consumption (C), investment (I), government spending (G), and net exports (exports minus imports) (X – M).

The sectoral balances relationship we derived in Chapter 5 brought together the expenditure sources of national income (consumption, investment, government and exports) with the uses of national income (saving, taxes, andimports).

To refresh your memory, the sectoral balances equation is:

(25.1)      (S – I) = (G – T) + (X – M)

The three sectoral balances are:

  • Private domestic balance (S – I) – will be in surplus if the private domestic sector spends less than its income (S > I).
  • Budget Deficit (G – T) – will be in surplus if the government raises more tax revenue than it spends (G < T).
  • Current Account balance (X – M) – will be in surplus if exports are higher than imports and net income flows (X > M)

Equation (25.1) tells us that the external balance (X – M) equals the sum of the private domestic balance (S – I) plus the budget balance (G – T), where private savings is S, private investment is I; public spending is G, taxes, T) and exports (X) minus imports (M) is the net savings of non-residents.

We can tell stories about what is going on in the economy by making assumptions about the relative magnitudes of these balances, noting always that the strict equality in Equation (25.1) is always ensured by movements in national income.

This is because we assume saving (S), tax revenue (T) and imports (M) are positive functions of income and thus rise when economic activity increases and fall when there is a decline in the level of output and income.

For example, when an external deficit (X – M < 0) and a public surplus (G – T < 0) coincide, there must be a private deficit.

Consider the following data. If X = 10 and M = 20 (using whatever currency units we like), (X – M) = -10 (a current account deficit). If G = 20 and T = 30, (T – G) = 10 (a budget surplus). Under these conditions, the right-hand side of Equation (25.1) will equal (20 – 30) + (10 – 20) = -20.

As a matter of accounting then, the private domestic balance, (S – I) = -20, which means that the domestic private sector is spending more than they are earning because I > S by 20.

So the fiscal drag from the public sector (budget surplus) is coinciding with an influx of net savings from the external sector, which finances the private domestic sector deficit spending. Is this situation sustainable? It all depends on the composition of the private sector spending. If the external deficit reflects private sector borrowing for investment, then the increased productive capacity may generate the returns necessary to sustain foreign debt levels indefinitely at low and stable levels. If the external deficit reflects a predominance of consumption imports the capacity of the private domestic sector to sustain the increasing foreign debt liabilities is limited.

The private domestic sector can only net save (S – I) > 0 when there is a current account deficit (X – M < 0), if the public budget deficit is large enough to, at least, just offset the current account deficit. Say, (X – M) = -20 (as above). Then a balanced budget (G – T = 0) will force the domestic private sector to spend more than they are earning (S – I) = -20. But a government deficit of 25 (for example, G = 55 and T = 30) will allow the private domestic to save by 15. You can see this by solving the right-hand side of Equation (25.1) as (55 – 30) + (10 – 20) = 15.

You can also see that if the private domestic sector is in balance (S – I = 0) then Equation (25.1) would become (X – M) = – (G – T), which is a direct relationship between the external and budget balances. In this form, we cannot infer causality from the accounting equality – do higher external deficits (X < M) drive higher budget deficits (G - T) or vice versa or is the relationship bi-directional? For example, a world recession where export income collapses may cause a trading economy with automatic stabilisers to experience a current account deficit, which then drives a rising budget deficit as national income falls as a result of the declining aggregate demand. We can re-arrange Equation (25.1) to express it more directly in the twin deficits hypothesis form: (25.2)      (X - M) = (S - I) + (T - G) Note that we are now expressing the budget balance as (T - G) with the interpretation that if T > G, then there is a budget surplus.

The Twin Deficits Hypothesis imputes a strict causality between the sectoral flows where the private sector savings and investment gap is zero or stable, and changes in the budget deficit translate directly into current account deficit.

This construction is used to justify the claims noted at the outset that a current account deficit represents a nation “spending more than it is earning” and this imbalance is caused by budget deficits which leads to increasing external debt.

Accordingly, the risk of foreign financial market retribution via downgrading by international ratings agencies and the like is related to rising budget deficits. The cure for a chronic current account deficit then is logically to be found in increased domestic savings emanating from budget surpluses.


NEXT PART OF THIS CHAPTER – Finish the Twin Deficits and Sustainability Of Budget Deficits discussion.

Saturday Quiz

The Saturday Quiz will be back again tomorrow. It will be of an appropriate order of difficulty (-:

That is enough for today!

(c) Copyright 2013 Bill Mitchell. All Rights Reserved.

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    4 Responses to Twin Deficits and Sustainability Of Budget Deficits – Part 1

    1. juanbeard says:

      A common view held by economists is that an increasing current account deficit indicates that a nation is “living beyond its means”
      I wonder if they recognize when using this statement that the inverse is implied: “current account surpluses indicate a nation is living below its means”
      For how long they think is “sustainable” to live below the means available and why is it needed? I don’t see much discussion about this. Maybe is part of a marketing strategy where they put this in a way most people think the way they want to.

    2. Minseong Kim says:

      From a long time ago, I had this question: I do get that current account deficit is not necessarily a bad thing.

      MMT says that current account deficit is capital account surplus, which is the desire of foreigners to save in domestic currency. But what if this is not the case? After all, all exporters-importers may just want to get their money back into their own currency. I know that there is an argument that “in order for exporters to export, there must be a funding chain,” so let’s suppose that banks provide funding chain. But what if domestic banks lack foreign currency that they can provide to foreigners? I don’t think banks can go like, “sorry. we can’t exchange money into your nation’s currency.” Or if banks were on short, I don’t think government can allow the banks to fail.

      I also saw from 3spoken (Neil Wilson) that liquidity actions are provided by central banks to fill-in the gap between foreign currency demand and supply ( Do you also agree with this? If so, how would this even be “flexible” foreign exchange rate setting?

    3. Fugue says:

      juanbeard – Living below your means doesn’t generally imply lost productivity, because the analogy used alongside this language is that of a household. Household savings are considered a good thing – you can save for a rainy day, you can put those savings to work by investing for future profit, you can be saving for something that isn’t feasible as a once off purchase.

      It’s the same reason why “living beyond your means” doesn’t make sense when talking of the government – the government isn’t like a household at all and the analogy is deceptive. Trying to adjust it to fit reality is accepting a flawed premise. You’ll note that, to a household, “putting savings to work by investing” generally means holding shares – understood to be providing capital for a private firm. Even though you’ve “bought” something, it’s an appreciating asset, not a consumer good or some other depreciating asset.

      For a government, “saving” is just draining liquidity from the economy. Investing in a private venture would be shown to be spending.

    4. kouassi says:

      What is the effect of the grant on the budget and current account nexus in developing countries? how can we mesaure it?

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