Massive changes to the US tax code are set to take effect in 2013 unless Congress acts. Key changes include: 1) a new 3.8% Medicare tax on investment income for high earners; 2) a new 0.9% Medicare tax on earned income for high earners; 3) a higher 10% floor for medical expense deductions. Other changes impact capital gains tax rates, ordinary income tax rates, dividend tax rates, AMT, payroll taxes, depreciation rules, and estate/gift taxes. The changes mean higher taxes for many individuals and businesses.