OPINION

JESSE M. FRANKL, CHAIRMAN.

The respondents have petitioned for review from the October 12, 1993 Finding and Award of the Commissioner for the Third District. On appeal, the respondents allege that the commissioner improperly applied the claimant's cost-of-living adjustment (COLA) increases to the cumulative compensation rate rather than against the base rate. We agree with their argument and reverse the trial commissioner's decision.

The claimant sustained a compensable injury to her right foot on January 7, 1990, which injury has left her temporarily totally disabled from employment. The claimant's base compensation rate was found to be $303.09. The commissioner determined that the claimant was entitled to a $26.00 COLA under 31-307a C.G.S. on October 1, 1990. She then became entitled to another COLA on October 1, 1991. The commissioner calculated the second COLA by multiplying the claimant's base rate and the $26.00 COLA by 2.5 percent. This resulted in a weekly compensation rate of $337.62. The respondent argues that the commissioner should not have included the $26.00 COLA in the amount multiplied, and the claimant's weekly compensation rate should have been $336.97.

Section 31-307a(a) provides in relevant part: "The weekly compensation rate . . . shall be adjusted annually . . . to provide the injured employee with a cost-of-living adjustment in his weekly compensation rate as determined as of the date of the injury under section 31-309. If the weekly compensation rate as determined under the provisions of section 31-309 . . . is greater than the maximum weekly compensation rate prevailing as of the date of the injury, the weekly compensation rate which the injured employee was entitled to receive at the date of the injury shall be increased by the percentage of the increase in the maximum weekly compensation rate required by the provisions of section 31-309 . . . ." (Emphasis added.) Prior to 1991, this section provided that the claimant's compensation rate shall be increased by the dollar amount of the increase in the maximum compensation rate, instead of by a percentage.

By its plain language, the statute increases the base compensation rate at the time of the injury by the percentage of the increase in the maximum compensation rate. The statutory formula does not contemplate an increase based in part on prior COLAs, as those take place after the time of the injury. This language is unambiguous, and we do not have discretion to construe it otherwise. All Brand Importers, Inc. v. Department of Liquor Control, 213 Conn. 184, 195 (1989).

The fact that prior COLAs might have been calculated based on a flat dollar amount rather than a percentage has no effect in calculating a claimant's entitlement to future adjustments to his or her base compensation rate. As the amicus curiae brief of the American Insurance Association pointed out, § 31-307a has never referred to accumulating annual increments. Prior to the 1991 amendments, COLAs spanning two or more years could be calculated by adding the individual dollar increases for each successive year because it made no difference in a claimant's compensation rate whether a commissioner looked at the overall change from the base rate to the current maximum rate, or whether he or she simply added the annual increases together year by year. In cases where the commissioner is contemplating both pre-amendment and post-amendment COLAs, however, the method of calculation is very important. Unless a claimant is already receiving the maximum base rate, pre-1991 dollar amount increases will be greater than the post-1991 percentage-based increases. Therefore, a COLA calculation based solely on the difference between the dollar amount of the maximum rate at the time of injury and the maximum in any given year will provide most claimants with more money than they would receive if the same COLA were calculated by comparing the two maximum rates and then multiplying the percentage of change by the claimant's base rate. It is the latter method that the legislature opted for in 1991.

Moreover, in Taylor v. P.J. Ladola's, 12 Conn. Workers' Comp. Rev. Op. 378, 1526 CRB-1-92-10 (Aug. 17, 1994), this Board concluded that the 1991 amendments to § 31-307a and § 31-309 C.G.S. applied retrospectively, as the changes they wrought were procedural, and the legislature's express intent was to reduce the amount of COLA payments. A claimant's entitlement to COLAs was not changed by the amendments; only the method of calculating those COLAs was altered. "Thus, the calculation of the amount of the COLA does not vest at the time of injury or disability." Id., 382.

Consistent with Taylor, we hold that the claimant's COLAs in this case should have been calculated solely using the statutory method in place at the time each calculation was made. Under the version of § 31-307a in effect on October 1, 1990, the claimant was entitled to her base compensation rate, increased by "the dollar amount of the increase in the maximum weekly compensation rate required by the provisions of section 31-309 from the date of the injury to [October 1, 1990]." Therefore, her compensation rate for the following twelve months was her base rate of $303.09 plus the $26.00 COLA corresponding to the change in the compensation rate for that year.

On October 1, 1991, however, the claimant's compensation rate became $303.09 plus "the percentage of the increase in the maximum weekly compensation rate . . . from the date of the injury to [October 1, 1991]. The maximum at the date of injury was $693.00, and the maximum on October 1, 1991 was $737.00. No longer is the $26.00 COLA from the previous year relevant; instead, the COLA will be based on the 6.3 percent difference between the two maximum rates. Thus, the claimant's compensation rate for the year following October 1, 1991 should be the base rate of $303.09 multiplied by 1.063 = $322.18. Both the $337.62 figure advanced by the claimant and the $336.97 figure advanced by the respondents are excessive, as each adds the $26.00 COLA from 1990 into the calculation at some point. Similarly, future COLAs should be calculated by multiplying the base rate by the percentage of the increase from the maximum rate at the date of the injury to "such October first," without considering prior COLAs at all.

We recognize that the trial commissioner's decision was based on common practice within the commission. Nonetheless, we cannot substitute our own judgment for that of the Legislature. Because the statutory language is unambiguous, we have no discretion in this matter. However, we believe this change in calculating the cost of living adjustment should be applied prospectively.

The trial commissioner's decision is reversed, and the case is remanded for an order consistent with this decision.

Commissioners Angelo L. dos Santos and Nancy A. Brouillet concur.