Yes. You may buy back the withdrawn ERS service after at least six months have passed since the date of your withdrawal. You can buy withdrawn ERS service credit if you:
Service can be purchased in one-month increments. The cost of this service credit includes the original withdrawn amount plus 10% interest for each fiscal year from the date of your withdrawal up to and including the fiscal year in which your purchase is completed. Interest is added each September 1.
Even though you were previously an ERS member, you cannot re-establish your account under the previous benefit rules. You will be subject to all current state laws for your annuity and health insurance eligibility after you pay for and re-establish your previously withdrawn service.