A lot of really big numbers are being tossed around in the wake of the special dividend announced by Microsoft Corp. last week. The dividend itself, at $3 a share, amounts to a $30 billion payout for the company, and a number of mutual funds with big blocks of Microsoft stock will get a hefty share of that, hundreds of millions of dollars in some cases.

But in most cases, the amount that finds its way through to shareholders will be pennies per share. This is because Microsoft is only a small percentage of the fund's holdings and because the fund has many thousands of shareholders. Still, fund managers say, those pennies will boost fund payouts this year noticeably.

For example, Microsoft was 3.2 percent of the portfolio of T. Rowe Price's Growth Stock Fund -- its No. 2 holding. The special dividend will add an estimated 8 cents per share to the fund's distribution to shareholders this year -- not a lot, you might say, but a big increase over the 3 cents managers had been predicting as of last month.

One place where the increased payout may not be entirely welcome is in tax-efficient or tax-managed funds, whose managers try to minimize taxable distributions. Microsoft was the No. 1 holding of Price's Tax-Efficient Growth Fund at 4 percent of the portfolio. As a result of the special dividend, the fund projects a distribution of 4 cents a share. Last month its projected distribution was zero. The good news is that the Microsoft dividend is expected to qualify for the 15 percent maximum federal tax rate.

Microsoft is scheduled to pay the dividend on Dec. 2 to shareholders who own the stock as of Nov. 17.

While Congress and the presidential candidates are busily debating the sources and effect of the burgeoning federal budget deficit, the government is leaving on the table enough uncollected taxes to wipe out at least half, and perhaps all, of this year's shortfall.

This money is the "tax gap," the difference between what the Internal Revenue Service ought to collect and what it actually collects. It is estimated at $250 billion to $311 billion, but in fact no one knows for sure. That is because Congress, in its wisdom, ordered the IRS back in the late '90s to stop doing the intense audits it used to keep up with cheaters.

The agency is working on a new round of research audits, which will be less "intrusive," and from which it hopes to extrapolate an accurate figure for how much money it is missing.

But meantime, IRS Commissioner Mark W. Everson told the Senate Finance Committee last week, "I don't have a best guess" as to what the real number is.

Senators on the Finance Committee pronounced themselves shocked, shocked, at this lack of data, though Finance is the very committee that in 1997 and '98 led the charge against the Taxpayer Compliance Measurement Program (TCMP) audits that had been the IRS's primary compliance research tool.

Using estimates from 2001 of $255 billion for the tax gap and 130 million returns, National Taxpayer Advocate Nina Olson figures that each taxpayer in effect had to cough up an extra $2,000 on average that year "to subsidize the unwillingness or inability of some taxpayers to pay their fair share."

And all these figures (except the number of returns -- the IRS does know that) could be low. The tax gap has three components, Everson noted -- returns that aren't filed, returns that are filed but don't show all the taxpayer's income, and returns where the tax due isn't paid in full.

Of the three, Everson said, the IRS has reliable numbers on only the last, and that's because it's self-evident from the return. For the rest, the agency has simply taken the last TCMP data -- from 1988 -- and increased them to match economic growth. It has had no way to gauge behavioral changes.

Everson said his agency is aggressively pursuing tax shelters and other instances of "egregious non-compliance," but other experts pointed to the underground cash economy as the place where the most tax dollars are lost.

Olson noted that IRS research indicates that when taxes are withheld from payments, such as wage withholding by employers, recipients report virtually all of that income. She, the Government Accountability Office and the Treasury Inspector General for Tax Administration have all recommended extending withholding to a variety of non-wage payments, though this has produced squawks from small business and other groups.

Based on IRS estimates, Sen. Max Baucus (Mont.), the Finance Committee's ranking Democrat, said a 1 percentage point increase in compliance would produce a $20 billion reduction in the federal deficit.

Baucus and panel Chairman Charles E. Grassley (R-Iowa) seemed enthusiastic about better collections. But when it comes to Congress -- and the White House, for that matter -- watch what they do, not what they say.

On the other side of Capitol Hill, a House Appropriations subcommittee voted earlier this month to lop $382 million off the IRS's $10.67 billion budget request for fiscal 2005.

That reduction would come off a request that the IRS Oversight Board, set up in 1998 to map long-term goals for the agency, believes was already $230 million short of what the IRS really needs because it didn't take into account higher salaries mandated by Congress, rising rents and other normal cost increases.

And it's actually harsher than that. The Bush administration's budget request contemplated a 1.5 percent pay rise for federal workers. The House Appropriations Committee last week voted for a 3.5 percent increase. If that stands, and history suggests it will, and the subcommittee's IRS cut remains, the agency will face what amounts to a budget cut at a time when the nation more than ever needs effective tax collection.

Sens. Grassley and Baucus said they intend to amend the pending Jumpstart Our Business Strength bill to extend the statute of limitations so that taxpayers who used the Son of Boss tax shelter and did not come clean with the IRS do not get off the hook by waiting. Absent a change, some Son of Boss participants would be able to run out the clock on the IRS by Aug. 15.