President Obama campaigned for re-election on a promise to take a larger share of taxable income above roughly $250,000 a year. The White House is now negotiating with Congressional Republicans, who instead want to raise some money by reducing tax deductions. Federal spending cuts also are at issue.

If a deal is not struck by year’s end, a wide range of federal tax cuts passed since 2000 will expire and taxes will rise for roughly 90 percent of Americans, according to the independent Tax Policy Center. For lower-income households, taxation would spike well above 1980 levels. Upper-income households would lose some but not all of the benefits of tax cuts over the last three decades.

Public debate over taxes has typically focused on the federal income tax, but that now accounts for less than a third of the total tax revenues collected by federal, state and local governments. To analyze the total burden, The Times created a model, in consultation with experts, which estimated total tax bills for each taxpayer in each year from 1980, when the election of President Ronald Reagan opened an era of tax cutting, up to 2010, the most recent year for which relevant data is available.

The analysis shows that the overall burden of taxation declined as a share of income in the 1980s, rose to a new peak in the 1990s and fell again in the 2000s. Tax rates at most income levels were lower in 2010 than at any point during the 1980s.

Governments still collected the same share of total income in 2010 as in 1980 — 31 cents from every dollar — because people with higher incomes pay taxes at higher rates, and household incomes rose over the last three decades, particularly at the top.

There are now many more millionaires, in other words, paying more than they did in 1980, but they are paying less than they would have if tax laws had remained unchanged. And while they still pay a larger share of income in taxes than the rest of the population, the difference has narrowed significantly.

The trend can be seen by comparing three examples:

¶A household making $350,000 in 2010, roughly the cutoff for the top 1 percent, on average paid 42.1 percent of its income in taxes, compared with 49 percent for a household with the same inflation-adjusted income in 1980 — a savings of about $24,100.