The basic retirement allowance of a member of Plan 1 of the Public Employees' Retirement System (PERS Plan 1) or the Teachers' Retirement System (TRS Plan 1) is equal to 2 percent of the member's average final compensation, calculated on the member's highest consecutive two years of compensation, for each year of service.  Retirement benefits in the PERS Plan 1 and TRS Plan 1 are available to members after 30 years of service at any age, with 25 years of service at age 55, and with five years of service at age 60.  The original Plan 1 design in both systems did not contain a benefit feature annually adjusting retirees' benefits, though several ad- hoc retiree benefit adjustments were created by the Legislature prior to 1995.

Between 1995 and 2011, PERS Plan 1 and TRS Plan 1 retirees' benefits could be eligible for an annual increase from a benefit generally referred to as the Uniform Cost of Living Adjustment (COLA), or Uniform COLA.  The Uniform COLA was enacted in 1995 to replace a number of prior COLAs and was a fixed dollar amount multiplied by the member's total years of service.  The dollar amount of the Uniform COLA was about $1.88 per year, meaning that a member with 25 years of service would receive an additional $47 per month each year, and the Uniform COLA itself would have increased by 3 percent per year on July 1.  Members did not have a contractual right to future increases to the Uniform COLA, and those increases ceased with the repeal of the Uniform COLA in 2011.
 
In 2018 the Legislature provided a one-time increase of 1.5 percent that was applied to the PERS Plan 1 and the TRS Plan 1 on July 1, 2018, up to a maximum increase of $62.50 per month.  In 2020 the Legislature again provided a one-time increase of 3 percent that was applied to the PERS Plan 1 and the TRS Plan 1, up to a maximum increase of $62.50 per month.

The PERS and TRS Plans 1 benefits for members retired by July 1, 2021, are increased by 3 percent on July 1, 2022, up to a maximum increase of $110.