On Jan. 1, dividend taxes are going up. And they may be going up a lot -- so much so that The Wall Street Journal is calling it the "dividend cliff."

How bad is it? Right now, the maximum dividend tax is 15%, the same rate as long-term capital gains. But for the wealthiest investors -- those making more than $200,000 a year or filing a joint return of $250,000 or more -- that rate could soar to 43.4%.

Those rate increases could kick in if Congress does not act. But there is the very strong likelihood that after the November elections, Congress will extend the current tax system for a year in order to figure out some more sensible changes. Right now, everything is in flux.

Even if Congress does act, the wealthiest investors will still face a new 3.8% surtax on dividends. That came out of President Obama's health care legislation. So even if the low rates are continued, the top dividend tax rate will rise to 18.8%.

Here's one example of how the surtax would work, according to The Journal. Say a married couple jointly reports $400,000 in income, including $160,000 in investment income. Their income is $150,000 above that $250,000 threshold, so the surcharge would apply to that $150,000 amount. They would owe $5,700 more in taxes.

Wealthiest investors could see dividend tax rates spike if Congress allows dividends to be taxed like ordinary income. In that case, the richest taxpayers could see the dividend rate go to 39.6% plus the 3.8% surtax.

The dividend tax hikes are a huge question mark for companies trying to figure out when to schedule their dividend payouts. Scheduling it before Jan. 1 makes sense, and it really makes no difference to companies financially if they speed up their dividend to meet the deadline, reports Jason Zweig of The Journal.

So expect to see increasing investor pressure on companies to pay out dividends in December instead of January. One company that is so far sticking firm to a January payout is Wal-Mart (WMT), which is holding on to its Jan. 3 payout date, Zweig reports. So far, the retailer shows no signs of moving that date. Other companies, like General Electric (GE), aren't saying what they're going to do.

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