By Adriel Bettelheim and Jonathan Allen, CQ Staff

The first family would have paid nearly $20,000 more in taxes this year under President Obama’s plan to cap the deductibility of charitable contributions for wealthy taxpayers.

He and first lady Michelle Obama donated $172,050, or about 6.5 percent, of their adjusted gross income of $2.66 million, to 37 charities.

Their donations are worth a deduction of $68,131.80 this year, based on qualifying for the top income tax bracket of 39.6 percent.

But under Obama’s plan, which would limit the applicability of deductions by couples making more than $250,000 to 28 percent of their contributions, the first couple would only have been able to claim $48,174 in deductions, costing them about $20,000.

That sum is a small portion of the Obamas’ income, which they revealed by releasing their tax return Wednesday afternoon.

The lion’s share of their earnings, $2.6 million, came from sales of the former Illinois senator’s books “Dreams From My Father” and “The Audacity of Hope.”

Since moving into the national spotlight (and becoming far more wealthy from the president’s books and the first lady’s promotions at the University of Chicago) the Obamas have been more generous with their money, according to the taxprof blog.

With an adjusted gross income of $207, 647 in 2004, for example, they gave $2,500. But the next year — Obama’s first in the Senate — they made $1.7 million and gave nearly $80,000 to charity.

Their income and gross charitable contributions peaked in 2007, when they donated $240,370 — about 5.8 percent of their income — to charities.

This year, the top recipients were an antipoverty organization called CARE and the United Negro College Fund, which each got $25,000. The Obamas helped fund a wide variety of religious, educational, anti-poverty, anti-homelessness, anti-hunger and civil rights groups.

They gave $5,000 to CURE, a charity run by White House senior adviser David Axelrod’s wife, Susan, that seeks a cure for epilepsy, which afflicts their adult daughter.

The Obamas gave no money to Trinity United Church of Christ, a congregation on the South Side of Chicago to which they once belonged and to which they donated more than $50,000 between 2005 and 2007. They resigned their membership in the church in the middle of 2008 after the controversial Rev. Jeremiah Wright became a persistent campaign issue.