WASHINGTON — As President Barack Obama mounts an aggressive campaign on what he calls tax fairness, his own tax burden has fallen to the lowest of his time in the White House, lower than many who make far less — including his secretary.

He and the first lady reported a joint adjusted gross income of $789,674 last year and paid $162,074 in federal taxes, or about 20.5 percent, according to the tax return released Friday by the White House. That income keeps the Obamas in the top 1 percent of taxpayers.

Their overall tax rate is slightly lower than average for people in the top tier, largely because they made significant donations to charity. Data compiled by the Tax Policy Center show the average income tax rate for those making more than $532,000 is 24 percent. Obama’s rate was closer to the average for households earning more than $210,000 — 19.2 percent

The Obamas’ overall rate was much higher than that of most middle-income Americans. Households making between $60,000 and $100,000 paid on average 8 percent of their income in federal income taxes, said the Tax Policy Center. Polling has shown most people think they pay more in income taxes than they do, in part because people focus on their marginal tax rate — the tax they pay on the last dollar they earn — not their average tax rate.

But the Obamas’ tax bite was slightly lower than the rate paid by his secretary, Anita Decker Breckenridge, who makes a $95,000 salary, the White House said Friday. The White House would not disclose what Breckenridge paid, saying it was a “slightly higher rate” than that of her boss.

That “is exactly why we need to reform our tax code and ask the wealthiest to pay their fair share,” said White House spokeswoman Amy Brundage.