When it comes to spending cuts, Congress is looking in the wrong place. Most federal nondefense spending, other than Social Security and Medicare, is now done through special tax rules rather than by direct cash outlays. The rules are used to subsidize a wide range of spending including education, child care, health insurance, and a myriad of other congressional favorites.
These tax rules—because they result in the loss of revenue that would otherwise be collected by the government—are equivalent to direct government expenditures. That's why tax and budget experts refer to them as "tax expenditures." This year tax expenditures will raise the federal deficit by about $1 trillion, according to estimates by the congressional Joint Committee on Taxation. If Congress is serious about cutting government spending, it has to go after many of them....
If tax expenditures are not cut, taxes on households and businesses will have to rise to prevent an explosion of the national debt, which is now projected to increase to 90% of GDP by 2020 from today's 63%. When benefits for Social Security and Medicare are set aside, the rest of the outlay side of the budget is too small—7.5% of GDP—to provide much scope for reducing annual budget deficits that are now projected to average 5% of GDP for the rest of this decade. In contrast, total tax expenditures are now 6.4% of GDP.
こうした特別措置は、それが無ければ政府によって徴収されたはずの収入の喪失をもたらすので、政府の直接支出と等価である。それが、税制や財政の専門家が「tax expenditure」よ呼ぶ所以である。今年のtax expenditureは、議会の合同税制委員会の見積もりによると、財政赤字を1兆ドル増加させるという。もし議会が財政支出削減に本気ならば、それらtax expenditureの多くを追及すべきだろう。・・・
もしtax expenditureが削減されないならば、今日のGDP比63%から2020年には90%に達すると見込まれる国家債務の爆発的膨張を防ぐため、家計や企業への税金を増やさざるを得ない。社会保障とメディケアへの支出を脇に置いておくとすると、残りの財政支出GDP比で7.5%であり、今後10年間に平均してGDP比5%になると見込まれる財政赤字を削減する余地を提供するにはあまりにも小さい。一方、tax expenditureの総額は現在GDPの6.4%である。

次に、マンキュー自身の11/20NYT論説「The Blur Between Spending and Taxes(支出と税金の区別の曖昧さ)」から。

Economists call the Blowhard plan a “tax expenditure.” The tax code is filled with them — although not yet one for snipe hunting. Every time a politician promises a “targeted tax cut,” he or she is probably offering up a form of government spending in disguise.

Erskine B. Bowles and Alan K. Simpson, the chairmen of President Obama’s deficit reduction commission, have taken at hard look at these tax expenditures — and they don’t like what they see. In their draft proposal, released earlier this month, they proposed doing away with tax expenditures, which together cost the Treasury over $1 trillion a year.

Such a drastic step would allow Mr. Bowles and Mr. Simpson to move the budget toward fiscal sustainability, while simultaneously reducing all income tax rates. Under their plan, the top tax rate would fall to 23 percent from the 35 percent in today’s law (and the 39.6 percent currently advocated by Democratic leadership).

This approach has long been the basic recipe for tax reform. By broadening the tax base and lowering tax rates, we can increase government revenue and distort incentives less. That should command widespread applause across the ideological spectrum. Unfortunately, the reaction has been less enthusiastic.

Pundits on the left are suspicious of any plan that reduces marginal tax rates on the rich. But, as Mr. Bowles and Mr. Simpson point out, tax expenditures disproportionately benefit those at the top of the economic ladder. According to their figures, tax expenditures increase the after-tax income of those in the bottom quintile by about 6 percent. Those in the top 1 percent of the income distribution enjoy about twice that gain. Progressives who are concerned about the gap between rich and poor should be eager to scale back tax expenditures.

Pundits on the right, meanwhile, are suspicious of anything that increases government revenue. But they should recognize that tax expenditures are best viewed as a hidden form of spending. If we eliminate tax expenditures and reduce marginal tax rates, as Mr. Bowles and Mr. Simpson propose, we are essentially doing what economic conservatives have long advocated: cutting spending and taxes.
経済学者は、Blowhard案(=この前段の例え話における税控除案)を「tax expenditure」と呼ぶ。税法はそれで満ち溢れている――ただし、(この前段の例え話の)シギ猟に関するものはまだ無いが。政治家が「目標を定めた減税」を約束するたびに、その政治家は、別の形に偽装した政府支出を提唱していると言える。
オバマ大統領の財政赤字削減委員会の委員長アースキン・B・ボウルズとアラン・K・シンプソンは、こうしたtax expenditureを詳細に調査し、問題が多いと結論づけた。今月初めに提出された彼らの案では、財政に年間1兆ドル以上もの負担を掛けているtax expenditureを無くすことを提案している。
左派の知識人は、富裕層の限界税率を下げるいかなる案も懐疑的な目で見る*1。しかし、ボウルズ氏とシンプソン氏が指摘したように、tax expenditureのもたらす便益は所得の上位層に偏っている。 彼らの示した数字によれば、tax expenditureは5分位の最下位層の税引き後所得を6%増やす半面、所得の最上位1%の層の利益はその2倍にもなる。貧富の差を懸念する進歩派たちは、tax expenditureの縮小に力を注ぐべきなのだ。
一方、右派の知識人は、政府収入を増やすいかなる案も懐疑的な目で見る。彼らは、tax expenditureは隠れた財政支出と見做すのが最も相応しいことを認識すべきだ。もしボウルズ氏とシンプソン氏が提唱するようにtax expenditureを削減し限界税率を低下させれば、事実上、経済の保守派たちが長らく提唱していたことを実行したことになる。即ち、財政支出と税の削減だ。

この後マンキューは、実際のtax expenditure削減の段になったら、各論反対が噴出するだろう、と予測している。たとえば住宅ローン金利の控除撤廃については、住宅保有者や不動産業界が強く反対するだろう、というわけだ。この住宅ローン金利控除についてマンキューは、以下のようにその経済合理性の欠如を指摘している。

  • 住宅ローン金利の控除は、高い法人税と相俟って、経済の資本形成を企業の資本から住宅の方に偏らせる。これは生産性ならびに実質賃金の低下を招く。
  • 住宅ローン金利の控除は、借家を持ち家に比べ不利にする。税制がそのような有利不利を決める謂れは無い。