United States President Barack Obama and first lady Michele Obama paid nearly 82,000 dollars in income tax in 2015 and donated 64,000 dollars to 34 charities, the White House reported Friday - tax day in the United States.The Obamas saw adjusted gross income of 436,065 dollars last year, according to their tax return. The U.S. president is paid a salary of 400,000 dollars per year. Obama also received just over 60,000 dollars in gross receipts for his work as an author, according to his tax return.Deductions were calculated to arrive at their adjusted gross income, which is the amount that is taxed. Their federal income tax was 81,472 dollars, an effective rate of 18.7 per cent.The first couple's donations to charity amounted to 14.7 per cent of their gross income. They also paid 16,017 dollars in state tax to Illinois, where the Obamas lived before he was elected president.Vice President Joe Biden and his wife Jill paid 91,546 dollars in federal tax in 2015 on adjusted gross income of 392,233 dollars - a tax rate of 23.3 per cent. They also contributed 6,620 dollars to charity."While we've made progress toward ensuring that the wealthiest Americans pay their fair share, there is more work to do," White House spokesman Josh Earnest said in a statement accompanying the tax return release."We need to close special tax loopholes for millionaires and billionaires and invest in the middle class."