With the tax deadline looming, some tax preparers who are dealing with more and more procrastinators cite capital gains changes as the culprit.

"I have never seen people being this late," said Carol Thompson, an enrolled agent in Monterey, Calif. "I think part of it is there is a new tax law, and everyone has been hearing about Schedule D and what a monster it is."The Internal Revenue Service said that as of April 3, 67.4 million taxpayers had filed their federal returns, slightly more than half the 124 million individual income tax returns expected this year. The number of returns filed was about 0.8 percent ahead of last year's pace, the IRS said.

"The overall impression is that the filing season is running very smoothly," said Joseph F. Lane of the National Association of Enrolled Agents, tax preparers licensed to practice before the IRS. Lane, who addressed a House Ways and Means subcommittee last week, credited the IRS with improved responsiveness to taxpayer complaints.

The 1997 tax bill reduced the maximum capital gains rate from 28 percent to 20 percent. The complex transition rules created by Congress caused the Schedule D capital gains worksheet to doubled in size to 54 lines from the year before.

Todd Ransom, H&R Block spokesman, said the company is expecting many taxpayers to pull out their tax paperwork for the first time after Easter dinner this Sunday. "They'll look at the Schedule D and say, `Oh my . . . what is it?' " Ransom said.

IRS spokesman Don Roberts said more than 1 million tax returns have been incorrectly filed without a Schedule D, even though the taxpayers reported capital gains on line 13 of their Form 1040s. The IRS will send the incomplete returns back to filers, asking them to add a Schedule D, which can further delay refunds.

Roberts said many of these cases appear to involve mutual fund investors who may not realize they have to file the paperwork to reflect capital gains distributions.

Another problem concerns errors by mutual funds and brokerage firms on Forms 1099, which provides taxpayers the amount of dividends, interest and capital gains to be included in a person's income tax return. Wall Street firms complained the various phase-in dates to obtain lower capital gains taxes made it difficult to calculate data for Form 1099 by the Jan. 31 deadline.

The Securities Industry Association said the error rate on Forms 1099 tripled to 17 percent for the 1997 tax year.

Charles Bish, an accountant with the Alexandria, Va., firm Bish & Haffey PC, said Thursday he had to amend returns for some clients who received corrected 1099 forms after the Jan. 31 deadline. "It's very frustrating," he said, considering that his clients generally have been filing earlier.

Despite earlier reported problems with bar codes on some IRS tax forms, the "IRS appears to be headed toward another generally successful filing season," the General Accounting Office said last week.

Its review of the first 2 1/2 months of 1998 showed "continuing improvement" in electronic filing and the ability of taxpayers to reach the IRS via telephone.