Washington — Social security will begin taking a bigger bite out of paychecks Friday, but benefits will drop for those who turn 65 and retire in 1982. The social-security payroll tax, 6.65 percent of earnings this year, rises to 6.7 percent in 1982. The maximum tax on wages also goes up almost $200 to $2,170 in 1982. Employers' contributions rise by the same amount. For a worker making $ 13,729, the change means a total of $919.84 to be deducted in 1982.