No matter who enters the White House in January, one thing is certain: The tax structure that business owners and their families now experience will change.

Here, we’ll attempt to flesh out some of the tax proposals by Democrat Barack Obama and Republican John McCain, and how they might affect your bottom line.

Income and business taxes

Obama’s tax plan would raise the top marginal federal income tax rate to 40 percent, which is where it stood before the Bush tax cuts of 2001 and 2003. That tax hike, however, won’t just hit wealthy individuals, but many of America’s 23 million small-business owners as well.

The Internal Revenue Service estimates 58 percent of those in the top tax bracket (approximately $250,000 in annual income and up) consist of small-business owners who file their federal taxes as personal income. If you’re among those who file that way, you’re going to take a tax hit.

Obama also would raise capital gains rates to between 20 percent and 28 percent for families making more than $250,000. His plans, however, do have goodies for small-business owners — including a tax credit for those who provide employee health care — and the elimination of capital gains taxes if the gains are poured back into the business.

“The vast majority of small businesses would face lower taxes under the Obama plan than under McCain’s plan,” said Obama economic adviser Jason Furman in a statement.

McCain, meanwhile, would keep the top rate at 35 percent; cut the corporate tax rate from 35 percent to 25 percent; and keep the capital gains tax rate where it is, at 15 percent.

The Republican also proposes allowing small-business owners to deduct the full amount of any new equipment and technology upgrades every year.

“The U.S. economy is in a weak state,” said John Taylor, a Stanford University economist and adviser to the McCain campaign, in August. “This is not the time to be raising anybody’s taxes.”

Death and taxes

If you are planning for the possibility that you won’t live through the next administration — which every smart business owner should do — the tax penalties for passing the business on to your heirs could vary greatly under each president.

Before the 2001 tax cuts, the federal government collected an estate tax of 55 percent on all inherited assets above a $1 million exemption. That rate will drop to 45 percent next year, be repealed for 2010 — and then return to the pre-2001 status quo in 2011.

Obama and McCain are united on this issue in one sense: Neither wants the estate tax to go back to the pre-2001 status quo. But they have very different ideas on how to change it.

McCain would match the estate tax rate to his proposed capital gains tax rate of 15 percent. And his tax would not apply at all to the first $10 million in assets a business owner would pass on to his or her children.

“The goal is to allow small business to grow and expand,” Doug Holtz-Eakin, a senior McCain economic adviser, told CNN Money.

Obama’s plan is to essentially keep the estate tax at the levels businesses will experience starting next year. The rate would be 45 percent, and apply to every dollar of value above $3.5 million for an individual, and $7 million for a married couple.

The U.S. Chamber of Commerce, which has been working to kill the “death tax” for years, doesn’t officially endorse presidential candidates, but it does endorse McCain’s estate tax policies.

“It’s the idea of visiting the undertaker and the IRS in the same day,” Bruce Josten, the Chamber executive vice president of government affairs, told CNN Money. “You think, ‘I paid taxes on this already.’”