After several days of apparent progress, negotiations on a deal to avoid the fiscal cliff stalled on Wednesday. House Speaker John Boehner, the lead negotiator for Republicans, is vowing to hold a vote on his own plan to raise taxes on people earning over $1 million a year, sparing most Americans from the loss of Bush-era tax hikes but leaving in place deep, potentially damaging automatic spending cuts due to hit at year's end. President Obama has threatened to veto Boehner's bill, known as Plan B, although it appears dead-on-arrival in the Democrat-controlled Senate. Obama said the GOP was refusing to strike a compromise due to a grudge against him, and he challenged Republicans to "peel off the war paint" and make a deal on a 10-year, $2 trillion deficit-cutting agreement to avoid the cliff. Each day without an agreement, though, increases the chance that the fiscal cliff will actually hit. Economists have warned that could trigger another recession. How would going over the cliff affect ordinary Americans? Here, a brief guide:

Would the fiscal cliff cause instant calamity?
Many people might panic right away if Jan. 1 arrives without a deal, but the real impact of the fiscal cliff will occur gradually as $600 billion in automatic tax hikes and spending cuts (mostly to defense and domestic spending programs) start kicking in. But the money won't be sucked immediately out of the economy. It will happen over the course of the year, although we'll all feel the pinch right away.

Where will we notice?
The first place most people will feel the pain is when they receive their first 2013 pay stub. Without a deal, the temporary reduction in the Social Security deduction — from 6.2 percent of pay to 4.2 percent — that was part of the economic stimulus package, will expire. The payroll tax will return to normal, and that extra 2 percent (of income up to $82,000) will go into the Social Security system instead of your pocket. That will add up to an average of $1,640 per taxpayer over the course of the year.

What about income taxes?
There, too, everyone will notice, although not everyone will suffer equally. The temporary tax cuts that then-president George W. Bush signed into law in 2001 and 2003 are set to expire for people at all income levels on Jan. 1. For married couples filing jointly, the rate will jump from 10 percent to 15 percent on the first $17,800 of adjusted gross income, it will remain at 15 percent on income from $17,800 to $60,350, and it will rise from 15 percent to 28 percent on income from $60,350 to $72,300. The taxes on a family making $80,000 will rise from 25 percent to 28 percent. Also, the standard deduction for married couples will fall from $12,100 to $10,150, and the child tax credit will fall from a maximum of $1,000 per kid to $500.

How much will that cost the average person?
It depends how much he or she makes. The nonpartisan Tax Policy Center estimates that if all of the scheduled tax increases are imposed, the average household will pay an extra $3,400 next year. The lowest fifth of households, with $11,239 in income, will pay an extra $412. The middle fifth, with an average income of $49,842, will pay $1,984 more. The second highest fifth (average income $80,080) will pay $3,540 more. The highest fifth (average income of $178,020) will pay an extra $14,173. The top 1 percent of taxpayers, those making $1.3 million on average, will see their tax bills rise by $120,537. That means that, in dollar terms, the super wealthy will pay the most, but those closer to the middle — say, couples making $80,000 — will lose the biggest chunk of their income.

So that's how much more we'll pay if there's no deal?
Not necessarily. Even if there's no deal to avoid every element of the fiscal cliff, there's a chance Congress will pass some form of a deal to ease the pain, at least for some of us. Boehner's bill would preserve the Bush-era tax cuts for almost everybody. Obama's proposal would keep those lower tax rates in effect for households making under $250,000 (which is still almost everybody). It's confusing, but there are plenty of online calculators available to help you estimate what you'll pay under all of the most likely scenarios (under Boehner's plan, under the Democrats' plan, if we simply go flying off the cliff). A single person earning $50,000, for example, would pay $10,313 in federal taxes (21 percent) if we went over the cliff, $9,753 under the GOP plan (20 percent tax rate), or $8,753 under Obama's plan (18 percent effective rate). Policy wonks say it's a good idea to take the calculators for a spin. "Some but not all of these tax hikes are still likely to go into effect as part of any deal to fix the nation's giant budget deficit," says Ian Salisbury at SmartMoney. "But just which ones is anybody's guess."

Sources: Bloomberg Businessweek, Reuters, Slate, SmartMoney, TIME, U.S. News & World Report, The Washington Post