For US federal tax, whether a taxpayer is subject to AMT is determined by a complicated way in Instructions for Form 1040, Line 45, which involves an incomprehensible "worksheet to see if you should fill in form 6251".
By simplification and approximation, is there a rule of thumb for an estimate of a salary value of a taxpayer, so that a salary above the value might cause the taxpayer to pay AMT with a big possibility, and a salary below the value might not with a big possibility?
Why do the following two sources seem to differ greatly in estimates of the boundary salary value:
http://www.bankrate.com/finance/taxes/alternative-minimum-tax-costly-complicated-1.aspx says that the possible boundary salary value for a single taxpayer to pay AMT is $53,900.
http://www.cnbc.com/2014/01/24/seven-triggers-alternative-minimum-tax.html says that
Taxpayers with small incomes fall within the AMT exemption limits. That leaves the upper middle class to face the tax, especially those with incomes between $200,000 and $500,000
Thanks.