After a long, frustrating period of tax uncertainty, people can now make tax planning decisions with a much greater degree of confidence. For some, that’s good news; for others, it’s a challenge.

Passage of the American Taxpayer Relief Act earlier this year means those with less than $200,000 in modified adjusted gross income — $250,000 for those married filing jointly — escape virtually all of the new taxes, phase-outs, and rate increases that became effective in January and will affect 2013 income tax returns. For those in higher brackets, however, there are a variety of income thresholds that will trigger new provisions and create new headaches.