One thing you can always count on is changes in tax rules. New from the Internal Revenue Service this year are potential breaks for dieters and fuel-efficient cars. And even existing breaks may require close attention to deadlines.

GREEN DRIVING. The IRS has approved a one-time, $2,000 "clean fuel deduction" for buyers of Toyota's hybrid Prius model, which runs on both electric power and gasoline. The deduction applies to model years 2001, 2002, and 2003 and is given even to taxpayers who do not itemize. An amended return can be filed for cars bought before this year. Also headed for approval are two Honda hybrids.

SHEDDING POUNDS. Serious dieters got a nod in April when the IRS said that combating a diagnosis of obesity can be a tax-deductible medical expense. That opened the way to deduct membership in a weight-loss program. Now the IRS says health clubs may also be deductible for weight loss. An auditor may balk if the club is overly plush or has lots of other activities. And high income may limit eligibility for medical deductions.

SIMPLE IRA. Taxpayers with modest self-employment income who move fast can use this special type of individual retirement account to shelter a big chunk of that income. As part of the plan, you can deposit a tax-deductible lump sum of up to $7,000 for 2002--even if that is all of your self-employment income. If you can afford to save like this, you have until October 1 to set up a Simple IRA for 2002.