You are required to contribute toward your retirement.

If your employer has adopted Section 70-a, your contribution rate is reduced by 5 percent or 8 percent (depending on which rate your employer provides). Since you are contributing less of your own money to the Retirement System, the annuity portion of your retirement benefit will be smaller. However, when you retire, an increased pension makes your total retirement benefit equal to the amount you would have received if you had continued to contribute at the full rate.