The burden of spending

Over the 12 months to October 2007, home prices in the 20 largest metropolitan areas declined by 6.1 percent. And they have fallen every month since January. With less equity to borrow from, homeowners could cut their spending. As a second whammy, a large volume of adjustable rate mortgages are scheduled to reset to higher interest rates between 2008 and 2012. The burden of higher monthly payments could force households to reduce their expenditures too.

Economic growth and consumer debt are inextricably connected in the U.S. And it’s been that way for so long that it’s easy to forget why and what that implies.

Spending has outpaced personal income since the mid 1980s. Households saved ten percent of disposable income in 1985, five percent in the mid 1990s, and then nothing in 2005. (See chart 1, maroon series, scale on the left axis.)

Chart 1 (click to enlarge)

Low interest rates motivated the consumption ramp-up. Loose monetary policy played its part, but it would be incorrect to blame it all on the Fed. The massive accumulation of wealth by developing countries lowered the opportunity cost of spending, as Alan Greenspan has explained.

Interest rates motivated it, but the borrowing spree was made possible by innovations in the financial sector that increased the supply of debt. The introduction of the FICO score in the early 1990s improved the assessment of a borrower’s creditworthiness – or at least lenders believe so. By pegging interest rates to an index, instead of offering fixed rates, lenders transferred some financial risk to borrowers. Securitization of debt balances shifted some more of that risk off the lenders’ balance sheets.

The problem with a growth path based on borrowing and spending is that it has a natural end. An individual’s debt limit is determined by her creditworthiness, income capacity and collateral. That limit may be high relative to current income, and it may even be unknown to the borrower — after all, it’s up to the lender to draw the line. But once debt balances reach that limit, spending can grow only as fast as income (minus debt payments). Consumption is pinned to the vagaries of income. At the aggregate level, that means that economic growth is more vulnerable to unemployment and to the swings of the stock and real estate markets.

For instance, back in 2001 unemployment was rising, investment fell sharply, and share prices crashed. But overall the economy held up better than expected. Why? One explanation lies in real estate wealth. That year house prices rose by nine percent and consumers borrowed against home equity.

As a gauge of the current level of indebtedness, households now spend almost 15 percent of their disposable income on interest payments, including mortgages. (See chart 1, blue series, scale on the right axis.) If you include repayment of principal, the fraction of debt payments is much larger. Debt repayments are linked to interest rates, and hence subject to unforeseeable increases. Hence the worry about mortgage resets.

The main variables that determine spending and access to debt are outside the policymaker’s control. The cost of borrowing depends on the world level and distribution of savings. Lenders will continue to improve their assessment and management of risk, thus reducing the cost of credit. And central banks are capable of controlling inflation, but not of preventing asset bubbles or stimulating long-run growth.

But don’t despair: tax policy can mend our spending ways. First of all, do no harm. Tax laws can distort the cost of borrowing. The Tax Reform Act of 1986 partially addressed this issue by getting rid of the deduction for interest paid on consumer debt (credit card and uncollateralized loans). The deduction for mortgage interest should go next. I concede that there’s a (weak) case for subsidizing home ownership. But these days a house is much more than a place to live: it’s a piggy bank to draw from. There is no reason why the government should subsidize that.

Second, replace the personal income tax with a tax on consumption. A basic tenet of economics is that if you tax something you get less of it. An income tax punishes work. Instead, the government could levy a tax on the difference between income and contributions to savings. The new tax could be progressive, rather than flat, and could include personal deductions, just like the current personal income tax.

The main obstacle to those tax policies is political. The mortgage interest deduction is popular, and a consumption tax is still regarded as an oddity. No presidential candidate who actually cares about being elected would make such proposals. Perhaps in 2012, if the then incumbent president can afford it. Changing the nature of American economic growth is a cause worthy of spending political capital on.

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