Q. How is the additional annuity calculated after you have passed 41 years 11 month of service?
A. Once you have reached the maximum earned annuity limit of 80 percent, any additional contributions you have made to the retirement system will be returned to you with interest. You may either keep the money or use it to buy additional annuity, which isn’t subject to the 80 percent limit. You can find out the cost of purchasing additional annuity at https://www.opm.gov/retirement-services/publications-forms/csrsfers-handbook/c031.pdf. Just scroll to Section 31A3.1-1.