When will the 'temporary' raid on Social Security end?

Another in a series of outsourced political commentary — this time from an unexpected source, Michael Hiltzik of the Los Angeles Times:

[W]ith every extension of the payroll tax holiday, which was first enacted in 2010, the prospect that Congress will ever restore the tax to its statutory 6.2% of covered income recedes a little bit further over the horizon. And that's bad medicine for Social Security.

To be fair, thus far the payroll tax holiday hasn't impaired Social Security's fiscal resources one bit. By law, 100% of the cut must be compensated for by transfers from the general fund; those transfers have come to about $130 billion since 2010, covering the original "temporary" one-year holiday and a two-month extension passed late last year.

The new extension will require a further transfer of about $94 billion, according to the Congressional Budget Office.

Yet because of the unique features of the program's financing, tampering with its revenue stream is playing with fire. The payroll tax is currently set at 12.4% of wages, split equally between employer and employee, up to a maximum of $110,100. The tax holiday cuts the employee's 6.2% share to 4.2%.

Sen. Tom Harkin (D-Iowa) put it well when he excoriated President Obama and his fellow congressional Democrats for approving a measure that places Social Security's financial stability on the table. "I never thought I would live to see the day when a Democratic president ... would agree to put Social Security in this kind of jeopardy," he said. "Never did I ever imagine a Democratic president beginning the unraveling of Social Security."

Even conservatives who aren't fans of the program's current structure acknowledge how hard it will be at any point in the foreseeable future to restore the old rate.

"Who is ever going to say, 'Now the economy's so strong that it's the right time to raise taxes'?" Andrew G. Biggs, a former Social Security official who is now a resident scholar at the American Enterprise Institute, told me.
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But the worst aspect of the payroll tax holiday is that it erodes Social Security's standing as a unique government program with its own revenue stream, a tax dedicated to its upkeep alone. …

The more the program has to rely on general income tax revenue, the shakier becomes its claim to being a special case among government expenditures. When program-slashers sharpen their axes in Washington, the line has always been drawn at Social Security because it's funded by a source distinct from the income tax.
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"If the holiday doesn't automatically expire," says [social security activist Eric] Kingson, "you're risking long-term economic security for a short-term economic gain, however important that is. We hope people understand that."