Final 2011 return:
Adjusted gross income: $13,696,961
Total federal tax paid: $1,935,708
Effective federal tax rate: 14.1 percent
Preliminary 2011 return (released in January):
Adjusted gross income: $20,901,075
Total federal tax paid: $3,226,623
Effective rate: 15.4 percent
Final 2010 return:
Adjusted gross income: $21,646,507
Total tax paid: $3,009,766
Effective rate: 13.9 percent
So here's the mystery: Between January and October of this year, Romney's adjusted gross income for 2011 fell by $7.2 million. And it dropped by nearly $8 million compared with his AGI in 2010. His federal tax liability also fell, by similar proportions.