Your federal tax rate is based on your income level and whether you are filing singly or jointly. The percentage can change annually. Below are the federal tax rates for 2013, 2014, and 2015.

2015 IRS Tax Rate Schedule
Tax Rate Single Filers Married and Filing Jointly or Qualifying Widow(er) Married and Filing Separately Head of Household
10% $0 - $9,225 $0 - $18,450 $0 - $9,225 $0 - $13,150
15% $9,226 - $37,450 $18,451 - $74,900 $9,226 - $37,450 $13,151 - $50,200
25% $37,451 - $90,750 $74,901 - $151,200 $37,451 - $75,600 $50,201 - $129,600
28% $90,751 - $189,300 $151,201 - $230,450 $75,601 - $115,225 $129,601 - $209,850
33% $189,301 - $411,500 $230,451 - $411,500 $115,226 - $205,750 $209,851 - $411,500
35% $411,501 - $413,200 $411,501 - $464,850 $205,751 - $232,425 $411,501 - $439,000
39.6% $413,201 and above $464,851 and above $232,426 and above $439,001 and above
2014 IRS Tax Rate Schedule
Tax Rate Single Filers Married and Filing Jointly or Qualifying Widow(er) Married and Filing Separately Head of Household
10% $0 - $9,075 $0 - $18,150 $0 - $9,075 $0 - $12,950
15% $9,076 - $36,900 $18,151 - $73,800 $9,076 - $36,900 $12,951 - $49,400
25% $36,901 - $89,350 $73,801 - $148,850 $36,901 - $74,425 $49,401 - $127,550
28% $89,351 - $186,350 $148,851 - $226,850 $74,426 - $113,425 $127,551 - $206,600
33% $186,351 - $405,100 $226,851 - $405,100 $113,426 - $202,550 $206,601 - $405,100
35% $405,101 - $406,750 $405,101 - $457,600 $202,551 - $228,800 $405,101 - $432,200
39.6% $406,751 and above $457,601 and above $228,801 and above $432,201 and above
2013 IRS Tax Rate Schedule
Tax Rate Single Filers Married and Filing Jointly or Qualifying Widow(er) Married and Filing Separately Head of Household
10% $0 - $8,925 $0 - $17,850 $0 - $8,925 $0 - $12,750
15% $8,926 - $36,250 $17,851 - $72,500 $8,926 - $36,250 $12,751 - $48,600
25% $36,251 - $87,850 $72,501 - $146,400 $36,251 - $73,200 $48,601 - $125,450
28% $87,851 - $183,250 $146,401 - $223,050 $73,201 - $111,525 $125,451 - $203,150
33% $183,251 - $398,350 $223,051 - $398,350 $111,526 - $199,175 $203,151 - $398,350
35% $398,351 - $400,000 $398,351 - $450,000 $199,176 - $225,000 $398,351 - $425,000
39.6% $400,001 and above $450,001 and above $225,001 and above $425,001 and  above