Approval process
Cost-of-living adjustments are granted to MTRS benefit recipients by vote of the Massachusetts Legislature. Every year, the Public Employee Retirement Administration Commission (PERAC) files with the Legislature a report detailing the increase or decrease in the Consumer Price Index (CPI). The Legislature then votes whether to grant a COLA based on the increase in the CPI or 3%, whichever is less.
Calculation
Currently, the retirement base on which a COLA is granted is $13,000. Accordingly, if the Legislature grants a 3% COLA effective July 1, a benefit recipient may have his or her allowance increased by a maximum of $390 per year, or $32.50 per month.
For your reference, the COLA for fiscal year 2013, effective July 1, 2012, is 3% on a base of $13,000.
Eligibility
| Recipient | When eligible to receive first COLA | To be eligible to receive the FY2013 COLA, effective July 1, 2012... |
| Retiree | After being retired for one full, July-through-June fiscal year | The retiree must have retired on or before June 30, 2011 |
| Survivor of Option C retiree | After the retiree has been retired for one full, July-through-June fiscal year | The Option C retiree must have retired on or before June 30, 2011 |
| Survivor of a member who died in active service | After one full, July-through-June fiscal year from the effective date of your survivor benefit | The member's date of death must have been on or before June 30, 2011 |
| Accidental death benefit recipient | After one full, July-through-June fiscal year from the effective date of your benefit | Your benefit must have begun on or before June 30, 2011 |
Historical notes
Prior to 1976, COLAs were automatic. The percentage was based on the previous year’s consumer price index (CPI) increase. In 1975, the Legislature repealed this formula, effective 1976. Beginning in 1981, the provisions of Proposition 2-1/2 required the state to fund all local government COLA costs. Prior to 1981, the state funded state and teacher retirees’ COLAs, while local governments were required to fund city, town and county COLAs.
From 1998 to 2011, the base remained at $12,000, for a maximum annual increase of $360. In November 2011, pursuant to Chapter 176 of the Acts of 2011, the base increased to $13,000 for a maximum annual increase of $390.
| Year | Allowed percentage | Retirement benefit base | Maximum annual amount | Notes |
| 1971 | 6.00% | of $6,000.00 | $360.00 | |
| 1972 | 4.30% | of $6,000.00 | $258.00 | |
| 1973 | 3.30% | of $6,000.00 | $198.00 | |
| 1974 | 6.20% | of $6,000.00 | $372.00 | |
| 1975 | 11.00% | of $6,000.00 | $660.00 | |
| 1976 | 5.00% | of $6,000.00 | $300.00 | |
| 1977 | 5.00% | of $6,000.00 | $300.00 | |
| 1978 | 6.50% | of $6,000.00 | $390.00 | |
| 1979 | 5.00% | of $6,000.00 | $300.00 | |
| 1980 | 6.00% | of $6,000.00 | $360.00 | |
| 1981 | 3.00% | of $7,000.00 | $210.00 | |
| 1982 | 3.00% | of $7,000.00 | $210.00 | |
| 1983 | 3.00% | of $7,000.00 | $210.00 | |
| 1984 | 4.00% | of $7,000.00 | $280.00 | |
| 1985 | 4.00% | of $8,000.00 | $320.00 | |
| 1986 | 4.00% | of $9,000.00 | $360.00 | |
| 1987 | 3.00% | of $9,000.00 | $270.00 | |
| 1988 | 4.00% | of $9,000.00 | $360.00 | |
| 1989 | NO COLA | |||
| 1990 | ||||
| 1991 | ||||
| 1992 | 5.00% | of $9,000.00 | $450.00 | effective 01/01/1992 |
| 1993 | NO COLA | |||
| 1994 | 3.00% | of $9,000.00 | $270.00 | |
| 1995 | NO COLA | |||
| 1996 | 3.00% | of $9,000.00 | $270.00 | effective 11/01/1996 |
| 1997 | NO COLA | |||
| 1998 | 2.10% | of $12,000.00 | $252.00 | |
| 1999 | 3.00% | of $12,000.00 | $360.00 | |
| 2000 | 3.00% | of $12,000.00 | $360.00 | |
| 2001 | 3.00% | of $12,000.00 | $360.00 | |
| 2002 | 3.00% | of $12,000.00 | $360.00 | |
| 2003 | 3.00% | of $12,000.00 | $360.00 | |
| 2004 | 3.00% | of $12,000.00 | $360.00 | |
| 2005 | 3.00% | of $12,000.00 | $360.00 | |
| 2006 | 3.00% | of $12,000.00 | $360.00 | |
| 2007 | 3.00% | of $12,000.00 | $360.00 | |
| 2008 | 3.00% | of $12,000.00 | $360.00 | |
| 2009 | 3.00% | of $12,000.00 | $360.00 | |
| 2010 | 3.00% | of $12,000.00 | $360.00 | |
| 2011 | 3.00% | of $12,000.00 | $360.00 | |
| 2012 | 3.00% | of $13,000.00 | $390.00 |
*Unless otherwise noted, all COLAs are effective on a fiscal year basis (e.g., the COLA listed as "2012," above, is effective for the fiscal year beginning July 1, 2012).