As akuperma points out, this is the end of a two-year payroll tax holiday, not an increase as such. There’s an article on the Forbes website (“Dear America: Your Higher Payroll Taxes Are Not The Result Of A Tax Increase”) that explains it nicely. Before you blame Obama, consider that the end of the payroll tax cut was not one of this issues of debate during the Fiscal Cliff negotiations — both parties supported it. Neither party thought it wise to continue the payroll tax holiday — it’s hard to run around like Chicken Little saying that Social Security is going broke while simultaneously saying that we should continue paying less money into the system.
For those of us who are self-employed, the tax goes up double (since we’re paying both the employer’s and employee’s contribution).