In the Supreme Court of Georgia

Decided: July 13, 2015 

S15A0366. TIBBLES v. TEACHERS RETIREMENT SYSTEM

OF GEORGIA et al.

BLACKWELL, Justice.

Following 31 years of service as a teacher in the public schools, Carol

Tibbles retired in April 1994. She is a member of the Teachers Retirement

System of Georgia, and as such, she is entitled by law to annual retirement

allowance in an amount

equal to 2 percent of [her] average compensation over the two

consecutive years of membership service producing the highest

such average, multiplied by the number of [her] years of creditable

service, not to exceed 40.

OCGA § 47-3-120 (a) (2). To calculate the amount of the allowance to which

Tibbles was entitled, the System looked to the compensation that she earned in

the 24 consecutive calendar months beginning with February 1992, and it

applied the statutory formula to that compensation. It appears that the System
consistently has paid Tibbles an allowance in an amount consistent with that

calculation.

Tibbles claims, however, that the System miscalculated the amount to

which she is entitled. First, she says, the statutory reference to “two consecutive

years” does not mean 24 consecutive calendar months. She argues that it instead

means 730 consecutive calendar days, unless one of those days is a leap day, in

which case, it means 731 consecutive calendar days. Second, Tibbles says, the

statutory reference to “average compensation” refers to compensation paid, not

compensation earned, in the pertinent two years. So, rather than looking to her

compensation earned in the 24 consecutive calendar months beginning with

February 1992, Tibbles urges, the System should have calculated her allowance

based upon the compensation that she was paid from Thursday, December 5,

1991 through Friday, December 4, 1993, including the paychecks that she

received on the first and last days of that period, the former of which was for her

work as a teacher in November 1991. 

Tibbles sued the System and its trustees, seeking legal and equitable relief

for the alleged miscalculation of her annual retirement allowance. The trial court

awarded summary judgment to the System, finding that the System adhered to

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its own rules and policies in calculating the amount to which Tibbles is entitled,

and concluding that those rules and policies comport with OCGA § 47-3-120 (a)

(2). Tibbles appeals, and we affirm.

1. This case concerns the meaning of OCGA § 47-3-120 (a) (2), and so,

we begin with the familiar and settled principles that inform our consideration

of statutory meaning. “A statute draws it meaning, of course, from its text.”

Chan v. Ellis, 296 Ga. 838, 839 (1) (770 SE2d 855) (2015) (citation omitted).

When we read the statutory text, “we must presume that the General Assembly

meant what it said and said what it meant,” Deal v. Coleman, 294 Ga. 170, 172

(1) (a) (751 SE2d 337) (2013) (citation and punctuation omitted), and so, “we

must read the statutory text in its most natural and reasonable way, as an

ordinary speaker of the English language would.” FDIC v. Loudermilk, 295 Ga.

579, 588 (2) (761 SE2d 332) (2014) (citation and punctuation omitted). “The

common and customary usages of the words are important, but so is their

context.” Chan, 296 Ga. at 839 (1) (citations omitted). “For context, we may

look to the other provisions of the same statute, the structure and history of the

whole statute, and the other law — constitutional, statutory, and common law

alike — that forms the legal background of the statutory provision in question.”

3
May v. State, 295 Ga. 388, 391-392 (761 SE2d 38) (2014) (citations omitted). 

Even reading the statutory text in this way, we sometimes may find that

the statutory text naturally and reasonably can be understood in more than one

way. When such a genuine ambiguity appears, it usually is for the courts to

resolve the ambiguity by ascertaining the most natural and reasonable

understanding of the text. See State v. Mulkey, 252 Ga. 201, 202-204 (2) (312

SE2d 601) (1984). But when it appears that the General Assembly has

committed the resolution of such an ambiguity to the discretion and expertise of

an agency of the ExecutiveBranch that is charged with the administration of the

statute, the usual rule may not apply. In those instances, the courts must defer

to the way in which the agency has resolved the ambiguity in question, so long

as the agency has resolved the ambiguity in the proper exercise of its lawful

discretion, and so long as the agency has resolved it upon terms that are

reasonable in light of the statutory text. See Cook v. Glover, 295 Ga. 495, 500

(761 SE2d 267) (2014). See also Center for a Sustainable Coast v. Coastal

Marshlands ProtectionCommittee, 284 Ga. 736, 741 (2) (670 SE2d 429) (2008).

4
This approach is not a new one.

1 Suttles v. Northwestern Mut. Life Ins. Co., 193

Ga. 495, 515 (4) (19 SE2d 396) (1942) (noting that a “[reasonable]

administrative interpretation and practice, continued for a long period, should

be accepted as controlling,” but “only when the law is ambiguous and

susceptible of different interpretations”). It reflects an acknowledgment that the

General Assembly properly may leave some matters to the discretion of the

Executive Branch, see Dept. of Transp. v. City of Atlanta, 260 Ga. 699, 703 (1)

(398 SE2d 567) (1990), as well as a recognition that some ambiguities may be

better resolved by officers and agencies of theExecutiveBranch, who can weigh

the policy implications of the ways in which an ambiguity reasonably might be

resolved in a way that courts cannot, and who can bring to bear specialized

knowledge and expertise that the courts lack. See Bentley v. Chastain, 242 Ga.

348, 350-351 (1) (249 SE2d 38) (1978). And for the most part, our approach is

consistent with the approach adopted by the United States Supreme Court in

Chevron, USA v. Natural Resources Defense Council, 467 U. S. 837 (104 SCt

1 As Professor David Shipley has explained, our Court has long adhered to this

approach, even if many of our earlier cases did not acknowledge it so explicitly. See David

E. Shipley, “The Chevron Two-Step in Georgia’s Administrative Law,” 46 GA.L.REV. 871,

888-916 (III) (2012). 

5
2778, 81 LE2d 694) (1984),2

as this Court recently acknowledged. See Cook,

295 Ga. at 500. With these principles in mind, we turn now to the questions of

statutory meaning presented in this case.

2. According to OCGA § 47-3-120 (a) (2), the amount of an annual

retirement allowance must be calculated with reference to “average

compensation over the two consecutive years of membership service producing

the highest such average,” OCGA § 47-3-120 (a) (2) (emphasis supplied), and

the parties dispute what is meant by “two consecutive years.” As we noted

2

 In Chevron, the United States Supreme Court described its approach in this way:

When a court reviews an agency’s construction of the statute which it

administers, it is confronted with two questions. First, always, is the question

whether Congress has directly spoken to the precise question at issue. If the

intent of Congress is clear, that is the end of the matter; for the court, as well

as the agency, must give effect to the unambiguously expressed intent of

Congress. If, however, the court determines Congress has not directly

addressed the precise question at issue, the court does not simply impose its

own construction on the statute, as would be necessary in the absence of an

administrative interpretation. Rather, if the statute is silent or ambiguous with

respect to the specific issue, the question for the court is whether the agency’s

answer is based on a permissible construction of the statute.

467 U. S. at 842-843 (II) (citations and footnotes omitted).

Because our approach predates Chevron bymany years, we have not adopted Chevron

and its progeny as our own, and our approach may not be perfectly consistent with the

Chevron approach in every respect and every application. That said, our approach does

closely resemble the Chevron approach in many respects, and both approaches reflect the

same sorts of concerns about judicial respect for the legislative commitment of certain

questions to the discretion of the Executive Branch and the special competence of officers

and agencies of the Executive Branch. For that reason, it often is useful to consult

Chevron and its progeny in applying our own approach. 

6
earlier, Tibbles says that “two consecutive years” means 730 consecutive

calendar days, unless one is a leap day, in which event, it means 731 consecutive

calendar days. For that reason, Tibbles argues, the statutory period of “two

consecutive years” can commence on any day. As reflected in its own

administrative rules and practices, however, the System understands the

statutory reference to “two consecutive years” to mean 24 consecutive calendar

months. See, e.g., Ga. Comp. R. & Regs., Rule 513-5-1-.08 (“The calculation

of average salary for retirement purposes shall allow the use of the salary earned

during any twenty-four (24) consecutive months producing the highest such

average . . . .”); Rule 513-5-.14 (1) (to calculate amount to which member is

entitled, “[s]elect a two-year period of twenty-four(24) consecutivemonths with

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the highest salary”).3

 A calendar month, of course, necessarily commences on

the first day of a month named in the calendar. 

(a) To begin, we consider whether the meaning of the statutory reference

to “two consecutive years” is unambiguous. Standing alone, the term could be

reasonably understood in more than one way. By definition, a “year” is a period

of twelve consecutive months, as the System contends, and it also is a period of

365 consecutive days (or 366 days in leap years), just as Tibbles argues. In its

ordinary usage, however, the term “year” — whether the “year” is measured in

months or days — is susceptible of different meanings so far as the specific

3 To be sure, these administrative rules do not explicitly provide that the 24

consecutive months must be calendar months. But according to the record, that is exactly

how the Systemhas consistently understood these rules, and indeed, the text of Rule 513-5-1-

.08 admits of no other understanding. In full, Rule 513-5-1-.08 provides:

The calculation of average salary for retirement purposes shall allow the use

ofthe salaryearned during anytwenty-four (24) consecutive months producing

the highest such average; not counting any month in which the member

normally would be under contract but for which no contributions were

reported, provided that additional months would be used only if the member

did not have credit for two (2) full years of service for the twenty-four (24)

month period.

(Emphasis supplied). The statutory law makes clear that contributions are remitted on the

basis of calendar months, with each school system required to remit employee contributions

by the tenth calendar day of the month following the month for which the contributions were

made. See OCGA § 47-3-42 (a). Because there is no reason to think that contributions would

be reported on any basis other than that on which they are remitted, Rule 513-5-1-.08 must

be understood to mean “calendar months” by its references to “months.” 

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points on the calendar at which a “year” can be said to begin and end. See State

ex rel. Gareau v. Stillman, 247 NE2d 461, 462 (Ohio 1969) (when used with

reference to “a period of 365 days,” the “word ‘year’ . . . is susceptible of

different meanings so far as the time within which the 365-day period should

begin and end”). See also Federal Trust Bank v. C. W. Matthews Contracting

Co., 312 Ga. App. 200, 202 & n.8 (1) (718 SE2d 63) (2011) (although a

“month” can mean “the period from a day of one month to the corresponding

day of the next month,” it also can mean “one of the months as named in the

calendar”). The ordinary usage of the word “year” does not resolve the question

presented in this case.

As used in our statutory law, the term “year” is presumed to refer to a

“calendar year,” OCGA § 1-3-3 (24), unless the context in which it is used

indicates otherwise. See Southerland v. Bradshaw, 255 Ga. 455, 456 (2) (339

SE2d 579) (1986). No party to this case contends that “two consecutive years”

means two consecutive calendar years — that is, two years beginning on January

1 of the first year — and indeed, the context of the statutory reference suggests

strongly that it means something other than calendar years. After all, OCGA §

47-3-120 (a) (2) speaks of “two consecutive years of membership service,” and

9
because academic years in the public schools of Georgia traditionally have

commenced in August or September, many new teachers would be expected to

begin to accrue “membership service” in months other than January. Cf. Bd. of

Ed. of Township of Manchester v. Raubinger, 187 A2d 614 (N.J. Super. A.D.

1963). For this reason, the presumptive statutory meaning is of no help either. 

Likewise, although the statutory usage of “two consecutive years” with

reference to “membership service” suggests strongly that it does not mean a

calendar year, this circumstance does not, without more, definitively resolve the

dispute with which we are presented. When used with reference to employment,

“[t]here are [various] types of year . . . . Employment is not inherently, or even

naturally, associated with any specific type of year . . . .” Mallin v. Nat. City

Mtg., No. 05-1499 SC, 2007 WL 4208336 at *4 (III) (B) (N.D. Cal. Nov. 27,

2007) (“year” may refer to “fiscal year, school year, tax year, lunar year, etc.”).

Indeed, in this case, a reasonable person might argue from the text of OCGA §

47-3-120 (a) (2) alone that “two consecutive years of membership service”

could refer to two consecutive academic years (commencing on the first day of

class), two consecutive teacher-contract years(commencing on the effective date

of a teacher contract), or two consecutive years of service as a teacher

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(commencing on the anniversary of the date upon which the member first began

to accrue “membership service”). Of course, no party to this case suggests that

OCGA § 47-3-120 (a) (2) refers to any of these sorts of years.

Nevertheless, the statutory reference to “two consecutive years” must be

considered in a context broader than just the words of OCGA § 47-3-120 (a) (2).

Looking to other sections of the statutory law concerning teacher retirement

benefits, see May, 295 Ga. at 391-392, we note that the statutes require the

remittance of employer and employee contributions to the System on the basis

of calendar months:

It shall be the duty of each county board of education, the board of

education of each independent school system, and of each and every

employer of teachers to deduct and collect the required employee

contributions from each teacher’s salary and to make monthly

remittance of such amounts to the [System]. Each employer shall

likewise make the required employer contribution and shall make

monthly remittance of such amounts to the [System] along with

employee contributions. Each employer shall remit the required

employee and employer contributions to the [System] by the tenth

calendar day of the month following the month for which the

contributions were made. In the case of the failure or refusal of the

employer to remit the employee and employer contributions on or

before the tenth calendar day of the month following the month for

which the contributions were made, there shall be added to the total

amount of remittance due the sum of 1 1⁄2 percent of the amount of

the remittance if the failure or refusal is for not more than one

11
month, and an additional 1 1⁄2 percent for each additional month or

fraction of a month during which the failure or refusal continues.

OCGA § 47-3-42 (a) (emphasis supplied). The statutes identify the date of

retirement by reference to calendar months: “The effective date of retirement

will be the first of the month in which the application is received by the

[System]; except that no retirement application will be effective earlier than the

first of the month following the final month of the applicant’s employment.”

OCGA § 47-3-101 (a). The statutes provide that the annual retirement allowance

is payable to a retired member on a monthly basis: “All retirement allowances

shall be payable in equal monthly installments . . . .” OCGA § 47-3-1 (24). And

the statutes clearly contemplate that these monthly payments of the allowance

are with reference to calendar months. See, e.g., OCGA§ 47-3-101 (c) (“Upon

the death of the retired member, all monthly benefits shall cease as of the end of

the month in which the retired member died.”). 

Especially because the statutes require the remittance of contributions and

payment of allowances on the basis of calendar months, the context of OCGA

§ 47-3-120 (a) (2) suggests that the statute means 24 consecutive calendar

months when it speaks of “two consecutive years.” Indeed, a strong argument

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can be made that this is the only natural and reasonable understanding of the

statutory reference to “two consecutive years.” Moreover, we find almost

nothing in OCGA § 47-3-120 (a) (2) or its context to suggest that “two

consecutive years” ought to be understood in terms of days, as opposed to

calendar months or some other measure of time.

4

 To the extent that the statute

is unambiguous on this point, the Systemproperly understood “two consecutive

years” in its calculation of the amount of the allowance to which Tibbles is

entitled. 

(b) In the alternative, even if the statutory reference to “two consecutive

years” were ambiguous, the way in which the System has consistently

understood the term would be entitled to deference, and so, we ultimately would

reach the same conclusion. Statutory ambiguity would require as the next step

4 The best argument that can be made for measuring “two consecutive years” in days

is the statutory direction to the System to identify “the two consecutive years of membership

service producing the highest . . . average [compensation].” OCGA § 47-3-120 (a) (2)

(emphasis supplied). Tibbles says that the direction to identify the period “producing the

highest such average” defines the term “two consecutive years,” and if a daily measure of

“two consecutive years” would produce the highest average compensation for a particular

member, then that is the measure that the System must adopt for that member. But this

statutory direction is more naturally and reasonably understood, we think, to identify which

of the several “consecutive years of membership service” form the basis for the calculation

of the amount of an allowance, not to define the unit bywhich “two consecutive years” ought

to be measured. 

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in our analysis that we ascertain who properly ought to resolve that ambiguity.

Just as we noted earlier, a court is required to defer to an agency of the

ExecutiveBranch with respect to the resolution of a statutory ambiguity, so long

as the legislature has committed the resolution of that ambiguity to the

discretion of the agency, the agency has resolved it by a proper exercise of that

discretion, and the agency has resolved it upon terms that are reasonable in the

light of the statutory text. 

As the United States Supreme Court has explained with reference to the

Chevron doctrine:

[A]dministrative implementation of a particular statutory provision

qualifies for Chevron deference when it appears that Congress

delegated authority to the agency generally to make rules carrying

the force of law, and that the agency interpretation claiming

deference was promulgated in the exercise of that authority.

Delegation of such authority may be shown in a variety of ways, as

by an agency’s power to engage in adjudication or notice-andcomment rulemaking, or by some other indication of a comparable

congressional intent.

United States v. Mead Corp., 533 U. S. 218, 226-227 (I) (B) (121 SCt 2164, 150

LE2d 292) (2001). Explicit authority to engage in notice-and-comment

rulemaking is not the only way to show the requisite legislative commitment of

the matter to the discretion of the agency, and compliance with notice-and14
comment rulemaking requirements is not the only way to show that the agency

resolved the matter by way of a proper exercise of its discretion. See id. at 231

(II) (A) (noting that the United States Supreme Court has “sometimes found

reasons for Chevron deference even when no such administrative formality was

required and none was afforded”). See also Barnhart v. Walton, 535 U. S. 212,

222 (II) (122 SCt 1265, 152 LE2d 330) (2002). Even without notice-andcomment rulemaking, “it can still be apparent from the agency’s generally

conferred authority and other statutory circumstances that [the legislature]

would expect the agency to be able to speak with the force of law when it

addresses ambiguity in the statute . . . .” Mead, 533 U. S. at 229 (II) (A). Those

other circumstances that may be indicative of a legislative commitment of the

matter to the discretion of the Executive Branch include a charge to the agency

to supervise the statutory law at issue and to assume primary responsibility for

the subject of the law, see NationsBank of N.C. v. Variable Annuity Life Ins.

Co., 513 U. S. 251, 256-257 (II) (A) (115 SCt 810, 130 LE2d 740) (1995), a

statutory delegation of authority to the agency to execute and enforce the statute

in question and to prescribe such rules and regulations as may be necessary to

do so, see National Cable & Telecommunications Assn. v. Brand X Internet

15
Svcs., 545 U. S. 967, 980 (III) (A) (125 SCt 2688, 162 LE2d 820) (2005), and

“the interstitial nature of the legal question, the related expertise of the [a]gency,

the importance of the question to the administration of the statute, the

complexity ofthat administration, and the careful consideration the [a]gency has

given the question over a long period of time.” Barnhart, 535 U. S. at 222 (II).

Here, the record reflects that the administrative rules at issue were

promulgated under the Georgia Administrative Procedure Act (“APA”), OCGA

§ 50-13-1 et seq., but the record does not disclose whether they were

promulgated under theAPA’s notice-and-commentrulemaking provisions.5 See

OCGA § 50-13-4. If the rules were subject to the APA’s notice-and-comment

rulemaking requirements, and if they were adopted in a manner that was

consistentwith those requirements, then those circumstances would indicate that

the rules qualify for deferential treatment. See Pruitt Corp. v. Ga. Dept. of

Community Health, 284 Ga. 158, 159-160 (2) (664 SE2d 223) (2008) (rule or

regulation that has “undergone the scrutiny” of notice-and-comment rulemaking

5 The notice-and-comment rulemaking requirements apply to “the adoption,

amendment, or repeal of any rule, other than interpretative rules or general statements of

policy.” OCGA § 50-13-4 (a). In their briefs, the parties do not address whether the rules at

issue here were subject to these statutory requirements. We can decide this case without

resolving this question, and so, we do not resolve it today.

16
may be entitled to deference). But even assuming that the rules were not subject

to the notice-and-comment rulemaking provisions of the APA, we perceive

other indications that the General Assembly has committed the resolution of

ambiguities in the teacher retirement statutes to the discretion of the System and

that the System enacted the rules at issue in a proper exercise of that discretion. 

Indeed, the General Assembly has provided explicitly that “[t]he

administration and responsibility for the proper operation of the retirement

system and for placing [the teacher retirement statutes] into effect are vested in

the board of trustees,” OCGA § 47-3-26 (a), and it has expressly authorized the

System (through its board) to “establish rules and regulations for the

administration of the funds created by this chapter and for the transaction of its

business.” OCGA § 47-3-26 (b). In our view, these provisions give the System

“the authority to promulgate binding legal rules,” which it has done “in the

exercise of that authority.” National Cable, 545 U. S. at 980-981 (III) (A). In

addition, the Systemis “charged with the enforcement” of the teacher retirement

statutes “to an extent that warrants [deference].” NationsBank, 513 U. S. at 256

(II) (A). Moreover, the legal question presented here — involving the

calculation of retirement benefits — relates to the expertise of the System and

17
is important to its complex administration of the teacher retirement statutes. See

Barnhart, 535 U. S. at 222 (II). And the rules in question were adopted more

than 30 years ago and, therefore, are undoubtedly of longstanding duration. See

id. at 220 (II). See also Suttles, 193 Ga. at 515 (4). For these reasons, the

understanding of the System about the meaning of “two consecutive years,” as

reflected in its administrative rules, would be entitled to deference, so long as

that understanding is reasonable.

We cannot say that the System is unreasonable to understand “two

consecutive years” to mean 24 consecutive calendar months. In the first place,

as we explained in Division 2 (a), this understanding is, we think, a natural and

reasonable understanding of the text of OCGA § 47-3-120 (a) (2) (considered

in its proper context), and it arguably is the only natural and reasonable

understanding. Second, the record in this case does not show this understanding

to be generally inconsistent with the usual payroll periods for teachers. Indeed,

Tibbles (like many other teachers) appears to have been paid twice a month for

her teaching, and there is no proof that any school system calculates teacher pay

on a daily basis. Third, there is no indication that the System receives

information about member compensation other than in connection with the

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monthly remittance of contributions, and to the extent that its calculation of the

amount to which a member is entitled is based on this information, the

calculation necessarily would reflect compensation in terms of calendar months.

In all, we conclude that the System was not unreasonable to understand OCGA

§ 47-3-120 (a) (2) to mean 24 consecutive calendar months when it speaks of

“two consecutive years.” To the extent that the statutory reference to “two

consecutive years” is ambiguous, we would defer to the understanding of the

System.

3. At oral argument, counsel for Tibbles conceded that she had to prevail

on both of her contentions about the meaning of OCGA § 47-3-120 (a) (2) to

establish that the System miscalculated the amount of her annual retirement

allowance. Because her contention about the meaning of “two consecutive

years” is without merit, her claim of miscalculation fails, and we need not

address her remaining contention. The judgment of the trial court is affirmed.

Judgment affirmed. All the Justices concur.

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