举例：
两只单身狗，每只狗的可征税收入是90750美元
每只狗需缴税5156.25+25%*（90750-37450）=18481.25
两只单身狗结婚后分开报税的话
每只狗需缴税5156.25+25%*（75600-37450）+28%*（90750-75600）=18935.75
相比单身，每只结婚狗多交（28%-25%）*（90750-75600）=3%*15150=454.5美元
就是有15150的收入多交了3%的税：单身的话90750以上才到28%的bracket，结婚的话，
75600以上就到28%了
如果他们联合报税呢？
总收入90750*2=181500
交税29387.5+28%*（90750-75600）*2=37871.5
每只狗还是交37871.5/2=18935.75
所以从税务考虑，如果狗男女收入都超过75600，应该保持单身。
但如果已经结婚的话，应该联合报税，联合报税绝不可能比分开报交的钱多。
Single:
Taxable Income Tax Rate
$0 to $9,225 10%
$9,226 to $37,450 $922.50 plus 15% of the amount over $9,225
$37,451 to $90,750 $5,156.25 plus 25% of the amount over $37,450
$90,751 to $189,300 $18,481.25 plus 28% of the amount over $90,750
$189,301 to $411,500 $46,075.25 plus 33% of the amount over $189,300
$411,501 to $413,200 $119,401.25 plus 35% of the amount over $411,500
$413,201 or more $119,996.25 plus 39.6% of the amount over $413,200
Married Filing Jointly or Qualifying Widow(er):
Taxable Income Tax Rate
$0 to $18,450 10%
$18,451 to $74,900 $1,845.00 plus 15% of the amount over $18,450
$74,901 to $151,200 $10,312.50 plus 25% of the amount over $74,900
$151,201 to $230,450 $29,387.50 plus 28% of the amount over $151,200
$230,451 to $411,500 $51,577.50 plus 33% of the amount over $230,450
$411,501 to $464,850 $111,324.00 plus 35% of the amount over $411,500
$464,851 or more $129,996.50 plus 39.6% of the amount over $464,850
Married Filing Separately:
Taxable Income Tax Rate
$0 to $9,225 10%
$9,226 to $37,450 $922.50 plus 15% of the amount over $9,225
$37,451 to $75,600 $5,156.25 plus 25% of the amount over $37,450
$75,601 to $115,225 $14,693.75 plus 28% of the amount over $75,600
$115,226 to $205,750 $25,788.75 plus 33% of the amount over $115,225
$205,751 to $232,425 $55,662.00 plus 35% of the amount over $205,750
$232,426 or more $64,998.25 plus 39.6% of the amount over $232,425
Head of Household:
Taxable Income Tax Rate
$0 to $13,150 10%
$13,151 to $50,200 $1,315.00 plus 15% of the amount over $13,150
$50,201 to $129,600 $6,872.50 plus 25% of the amount over $50,200
$129,601 to $209,850 $26,772.50 plus 28% of the amount over $129,600
$209,851 to $411,500 $49,192.50 plus 33% of the amount over $209,850
$411,501 to $439,000 $115,737.00 plus 35% of the amount over $411,500
$439,001 or more $125,362.00 plus 39.6% of the amount over $439,000
For tax year 2015, the personal exemption amount is $4,000 (up from $3,950
in 2014).
Filing Status Standard Deduction
Single $6,300
Married Filing Jointly $12,600
Married Filing Separately $6,300
Head of Household $9,250
Qualifying Widow(er) $12,600
