12% is not even close to correct. 2008 US tax rate for single person making $50,000 a year was 25% for federal income tax only.
Source.
Source.
How Much Is The Tax Rate For A Single Male EARNING $50,000 YEAR?
The tax rate differs from country to country and depends on your marital status and family members. For a single male earning $50,00 per year it is 12% in the United States, 17% in United Kingdom, 18% in France, 19% in Canada etc.