There are two reasons to be concerned when a government runs persistent budget deficits. We described one reason in Chapter 10 where the concept of crowding out was defined: when the economy is at full employment and the government borrows funds in the financial markets, it is competing with firms that plan to borrow funds for investment spending. As a result, the government’s borrowing may crowd out private investment spending, increasing interest rates and reducing the economy’s long-run rate of growth.

But there’s a second reason: today’s deficits, by increasing the government’s debt, place financial pressure on future budgets. The impact of current deficits on future budgets is straightforward. Like individuals, governments must pay their bills, including interest payments on their accumulated debt. When a government is deeply in debt, those interest payments can be substantial. In fiscal 2013, the U.S. federal government paid 1.3% of GDP—$221 billion—in interest on its debt. The more heavily indebted government of Italy paid interest of 5% of its GDP in 2013.

Other things equal, a government paying large sums in interest must raise more revenue from taxes or spend less than it would otherwise be able to afford—or it must borrow even more to cover the gap. And a government that borrows to pay interest on its outstanding debt pushes itself even deeper into debt. This process can eventually push a government to the point where lenders question its ability to repay. Like a consumer who has maxed out his or her credit cards, it will find that lenders are unwilling to lend any more funds. The result can be that the government defaults on its debt—it stops paying what it owes. Default is often followed by deep financial and economic turmoil.

Americans aren’t used to the idea of government default, but such things do happen. In the 1990s Argentina, a relatively high-income developing country, was widely praised for its economic policies—and it was able to borrow large sums from foreign lenders. By 2001, however, Argentina’s interest payments were spiraling out of control, and the country stopped paying the sums that were due. In the end, it reached a settlement with most of its lenders under which it paid less than a third of the amount originally due.

In 2010–2013 investors placed a fairly high probability on Argentine-type default by several European countries—namely, Greece, Ireland, and Portugal—and were seriously worried about Italy and Spain. Each one was forced to pay high interest rates on its debt by nervous lenders, exacerbating the risk of default.

Default creates havoc in a country’s financial markets and badly shakes public confidence in both the government and the economy. Argentina’s debt default was accompanied by a crisis in the country’s banking system and a very severe recession. And even if a highly indebted government avoids default, a heavy debt burden typically forces it to slash spending or raise taxes, politically unpopular measures that can also damage the economy. In some cases, austerity measures intended to reassure lenders that the government can indeed pay end up depressing the economy so much that lender confidence continues to fall.

Some may ask: why can’t a government that has trouble borrowing just print money to pay its bills? Yes, it can if it has its own currency (which the troubled European nations don’t). But printing money to pay the government’s bills can lead to another problem: inflation. In fact, budget problems are the main cause of very severe inflation. Governments do not want to find themselves in a position where the choice is between defaulting on their debts and inflating those debts away by printing money.

Concerns about the long-run effects of deficits need not rule out the use of expansionary fiscal policy to stimulate the economy when it is depressed. However, these concerns do mean that governments should try to offset budget deficits in bad years with budget surpluses in good years. In other words, governments should run a budget that is approximately balanced over time. Have they actually done so?