The funding gap for Medicare and Social Security may be the nation's biggest, and scariest, long-term fiscal problem. But who would have thought an obscure agency called the Federal Accounting Standards Advisory Board would be the first part of the government to address it head-on?

The board, established in 1990, tells the federal bureaucracy how to produce a set of audited financial statements. Essentially, it does for the government what the similarly named Financial Accounting Standards Board does for private corporations.

The FASAB issued a proposal last month that should resonate well beyond the green-eyeshade crowd: It wants Uncle Sam to recognize Social Security and Medicare obligations as a liability.

In the arcane world of government financial statements, this is a huge step. It would add something like $39 trillion in liabilities, quintupling the accountants' measure of what the government owes. It also, proponents hope, would make non-accountants sit up and take notice.

"People are concerned about generational equity, and that's what a liability on the balance sheet really measures," says David Mosso, chairman of the FASAB. "It's a first measure of a generational transfer. It's also a good measure of what future funding measures we will have to take. It helps to inform the political debate.

"Accountants are just good scorekeepers," Mosso continued. "Our obligation is to put reliable information out there so policymakers can use it in making decisions, and the public can use it when addressing their representatives in Congress."

In this case, the scorekeeper might influence the outcome of the game. If an eye-popping figure like $39 trillion stirs up public concern, Congress and the president may have to confront an issue that they've been able to ignore until now.

Perhaps that's why the FASAB's three government representatives prefer not to recognize the social-insurance liability, while its six independent board members all favor the proposal. The agency is taking comments on the issue until April, and the rules aren't likely to change until fiscal 2010.

The proposed change won't affect the annual budget process or the widely reported measure of the federal budget deficit. Those numbers are reported on a cash basis. Nor will it affect the Social Security trustees' annual report, which uses actuarial estimates. But the Treasury also prepares a report using accrual accounting, similar to the way a private company does, and that report must follow FASAB standards.

Until now, the thinking has been that Social Security and Medicare benefits are merely political promises on which a future Congress could renege.

Murray Weidenbaum, a Washington University economist and veteran of Washington budget battles, sees some validity to that treatment. "These are liabilities maybe in an accounting sense, but not in a legal sense," he said. "There's nothing, other than constituent anger, to prevent Congress from changing them. I certainly wouldn't put these benefits in the same category as Treasury securities."

But Stephen Moehrle, a professor of accounting at the University of Missouri, likes the FASAB proposal. "These benefits meet the classic definition of a contingent liability, which involves two questions: Is it estimatable, and is it reasonably probable to be paid? Absent some tangible evidence that the liability will be reduced or eliminated, I think you should go ahead and record that liability."

This is likely to become far more political than your garden-variety accounting issue. But after so many years of buck-passing on Social Security and Medicare, a high-profile debate is exactly what the nation needs.

David Nicklaus is a columnist for the St. Louis Post-Dispatch.