WASHINGTON—GOP presidential candidate Mitt Romney paid a 14% effective income tax rate in 2010 after making $3 million in tax-deductible charitable donations and drawing most of his income from investments, according to a summary of Mr. Romney’s 2010 tax form provided by his campaign.

Mr. Romney reported $21.7 million in income. He paid $3 million in federal taxes, slightly more than the $2.98 million he made in charitable donations. At least $1.5 million of his charitable donations went to the Mormon Church.

Of Mr. Romney’s 2010 income, he noted a capital gain of $12.6 million, taxable interest of $3.3 million, ordinary dividends of $4.9 million and smaller sums of gains and losses on business income, refunds and other income. . .