If you're among the millions of converts to do-it-yourself tax software, you might be ready for the next step: Online tax preparation. There are dozens of Web-based programs that will help you electronically prepare, store, and file your tax returns, either free or for a relatively modest charge.

Fortunately, all of those services are easy to try. They guide you through the tax-prep process or, if you're experienced, let you skip to the topics that relate to you. Most don't charge you anything until you file. If you have the time and inclination, you can test as many as you'd like to see which one delivers the greatest tax savings. Consider these points before you try one out:

• Check which of the IRS forms and schedules the site supports. Most sites provide Form 1040 and Schedule A for itemized deductions, but they might not handle more-specialized forms. For example, www.isecuretax.com does not include Form 1040-SS, the U.S. Self-Employment Tax Return, or Form 2210, Underpayment of Estimated Tax.

• Make sure the site can handle your state taxes. At www.eztaxreturn.com, for example, you pay $39.95 to prepare and file a federal and state return, but it only supports tax returns for 17 states.