WASHINGTON -- In addition to tax law revisions that affected the just-ending 1998 tax year, the following changes for 1999 will take effect New Year's Day:
-- The credit for children under age 17 for middle-class parents rises to $500 from the $400 credit allowed in 1998.
-- Self-employed people will be able to deduct 60 percent of their health insurance premiums in 1999, up from 45 percent in 1998.
-- An expanded definition of the home office means an estimated 2 million business people will be able to claim a deduction for the first time on 1999 returns.
-- Senior citizens aged 65-69 can earn up to $15,500 in 1999 without losing any of their Social Security benefits, compared with $14,500 in 1998. The limit increases to $30,000 in 2002.
-- Beginning Jan. 19, the Internal Revenue Service cannot seize a taxpayer's principal residence without a court order. Several other taxpayer protections also take effect in 1999.
-- The amount of income subject to the 12.4 percent payroll tax that funds Social Security rises from $68,400 in 1998 to $72,600 in 1999. This is the largest such increase since 1979 and translates into a tax increase on 9 million people.