FOR PUBLICATION

UNITED STATES COURT OF APPEALS

FOR THE NINTH CIRCUIT

CINDY R. CASTILLO, individually and 

on behalf of all others similarly 

situated,

Plaintiff-Appellant,

v.

BANK OF AMERICA, NA, a North 

Carolina Corporation; DOES, 1–10, 

inclusive,

Defendants-Appellees.

No. 19-56228

D.C. No.

8:17-cv-00580-

DOC-KES

OPINION

Appeal from the United States District Court

for the Central District of California

David O. Carter, District Judge, Presiding

Argued and Submitted September 3, 2020

Pasadena, California

Filed November 18, 2020

Before: Ronald M. Gould and Sandra S. Ikuta, Circuit 

Judges, and David A. Ezra,* District Judge.

Opinion by Judge Gould

* The Honorable David A. Ezra, United States District Judge for the 

District of Hawaii, sitting by designation.
2 CASTILLO V. BANK OF AMERICA

SUMMARY**

Class Certification

The panel affirmed the district court’s order denying a 

plaintiff’s motion to certify a class regarding her overtimewage claim under California law against Bank of America, 

N.A.

The plaintiff sought to certify a class of hourly-paid, nonmanagerial call center workers. The panel held that she 

established the requirements of commonality and typicality 

under Fed. R. Civ. P. 23(a)(2)–(3), but not predominance 

under Rule 23(b)(3) because the challenged Bank of 

America policy either did not apply or did not cause injury 

to many employees.

COUNSEL

Mitchell J. Murray (argued), James R. Hawkins, Gregory 

Mauro, and Christina M. Lucio, James Hawkins APLC,

Irvine, California, for Plaintiff-Appellant.

Kathryn M. Barber (argued) and Matthew A. Fitzgerald,

McGuireWoods LLP, Richmond, Virginia; Matthew C. 

Kane, McGuireWoods LLP, Los Angeles, California; Sylvia 

J. Kim, McGuireWoods LLP, San Francisco, California; for 

Defendants-Appellees.

** This summary constitutes no part of the opinion of the court. It 

has been prepared by court staff for the convenience of the reader.
CASTILLO V. BANK OF AMERICA 3

OPINION

GOULD, Circuit Judge:

This appeal arises from a dispute regarding the proper 

method of calculating overtime wages under California law. 

Plaintiff Castillo sought to represent a class of more than 

5,000 hourly-paid, non-managerial call center workers in 

California for numerous wage and hour violations allegedly 

committed by Defendant Bank of America, National 

Association (“BOA”). As relevant to this appeal, Castillo 

sought to certify a class regarding her overtime-wage claim. 

BOA maintains that Castillo did not satisfy the mandatory 

requirements of commonality and typicality, under Fed. R. 

Civ. P. (FRCP) 23(a)(2)–(3), or the requirement, mandatory 

in the circumstances here where it is the only basis asserted 

for satisfying FRCP 23(b), of predominance of common 

issues.1 FRCP 23(b)(3).

In response to Castillo’s Motion for Class Certification, 

the district court found that Castillo had satisfied the 

requirements of commonality and typicality under FRCP 

23(a)(2)–(3), but not predominance under FRCP 23(b)(3). 

This appeal followed.

We hold that: (1) Castillo has established commonality; 

(2) Castillo has established the typicality of her claim; but 

that (3) Castillo has not established predominance, which 

was essential to Castillo’s class action claim, because the 

challenged BOA policy either did not apply or did not cause 

1 See FRCP 23 and Zinser v. Accufix Rsch. Inst., 253 F.3d 1180 (9th 

Cir. 2001).
4 CASTILLO V. BANK OF AMERICA

an injury to many employees.2 Accordingly, we affirm the 

district court’s denial of class certification.

2 Rule 23(b) provides that a class action can be maintained if one of 

its elements is present, and the only 23(b) factor asserted by Castillo is 

FRCP 23(b)(3), common issue predominance. The full text of Rule 

23(b) reads:

(b) TYPES OF CLASS ACTIONS. A class action may 

be maintained if Rule 23(a) is satisfied and if:

(1) prosecuting separate actions by or against 

individual class members would create a risk of:

(A) inconsistent or varying adjudications with respect 

to individual class members that would establish 

incompatible standards of conduct for the party 

opposing the class;

or

(B) adjudications with respect to individual class 

members that, as a practical matter, would be 

dispositive of the interests of the other members not 

parties to the individual adjudications or would 

substantially impair or impede their ability to protect 

their interests;

(2) the party opposing the class has acted or refused to 

act on grounds that apply generally to the class, so that 

final injunctive relief or corresponding declaratory 

relief is appropriate respecting the class as a whole; or

(3) the court finds that the questions of law or fact 

common to class members predominate over any 

questions affecting only individual members, and that 

a class action is superior to other available methods for 
CASTILLO V. BANK OF AMERICA 5

I

This case arises from a dispute regarding the proper 

method of calculating overtime wages under California law. 

Under California law, employers must pay non-exempt 

employees who work overtime a premium on top of their 

“regular rate of pay.” Cal. Labor Code § 510(a); see also 

Alvarado v. Dart Container Corp. of Cal., 411 P.3d 528, 533 

(Cal. 2018).

Castillo worked as an hourly employee at a BOA call 

center until September 2016. BOA operates thirteen call 

centers in California where, from March 2013 to September 

2018, BOA employed 5,031 employees to handle calls 

regarding banking and investment services offered by BOA.

During this period, employees could receive a flat-sum, 

nondiscretionary incentive bonus ranging from $350 to 

$2,100 per month. If employees worked overtime and 

received a bonus during the same period, BOA would apply 

the bonus to the employee’s straight pay to calculate the 

fairly and efficiently adjudicating the controversy. The 

matters pertinent to these findings include:

(A) the class members’ interests in individually 

controlling the prosecution or defense of separate 

actions;

(B) the extent and nature of any litigation concerning

the controversy already begun by or against class 

members;

(C) the desirability or undesirability of concentrating

the litigation of the claims in the particular forum; and

(D) the likely difficulties in managing a class action.
6 CASTILLO V. BANK OF AMERICA

employee’s regular rate of pay for purposes of overtime 

premiums.

BOA’s methods of payment can be divided into two 

separate periods. These periods are distinguished by both 

the time period and the way bonuses were calculated and 

paid. 

During the first period, BOA “divided the incentive pay 

amount by the number of total hours worked in the previous 

two pay periods, even if those two pay periods did not 

coincide with the month for which the incentive pay 

compensated, then multiplied that amount by the overtime 

hours worked in those pay periods.”

For the second period, BOA used another method. 

Under this second method, BOA “divide[d] the month’s 

incentive pay by weekdays in the month regardless of how 

many days an employee actually worked that month.” BOA 

then “multiplie[d] that number by five, representing the days 

worked in a week, regardless of how many days an employee 

actually worked.” BOA then divided “that number by total 

hours worked instead of only non-overtime hours worked.” 

Finally, BOA would then divide “that number by two to get 

the new overtime ‘half rate,’ which it multiplied by the 

overtime hours worked to retroactively pay the underpaid 

overtime amount.”

In March 2017, Castillo filed a Class Action Complaint 

against Defendant-Appellee BOA. After several 

amendments and motions to dismiss, including one that was 

granted in part and denied in part, Castillo filed her Fifth 

Amended Complaint. Castillo alleged three claims for 

(1) “failure to pay minimum wages,” (2) “failure to 

accurately pay overtime wages,” and (3) “failure to provide 

second meal periods.” Castillo also made several additional 
CASTILLO V. BANK OF AMERICA 7

claims (the Fifth, Sixth, and Seventh Causes of Action) that 

were derivative of the three substantive claims. 

Castillo moved for class certification in May 2019. In 

opposition to class certification, BOA submitted several 

evidentiary objections and a motion to strike certain 

evidence, which the district court denied, stating that it 

would “not engage with such frivolous objections at the class 

certification stage.” However, the district court refused to 

consider a supplemental expert report filed with Plaintiff’s 

Reply to Defendant’s Opposition, on the basis of which 

Castillo argued that she was undercompensated by $14.99. 

The district court reasoned that the belated proffer of new 

opinions and data were improper.

The district court denied class certification. For both the 

first and third claims—the minimum wage claim and the 

meal break claim—the district court found no commonality, 

no typicality, and no predominance. On the second claim—

the overtime-wage claim—the district court found 

commonality and typicality, but found that there was not 

predominance.

Challenging only the denial of the second claim—the 

overtime-wage claim—and any claims derivative of it, 

Castillo timely appealed. FRCP 23(f). The district court had 

jurisdiction under 28 U.S.C. §§ 1331, 1332(d)(2), & 1367, 

and we have jurisdiction under 28 U.S.C. § 1292(e).

II

“A district court’s class certification ruling is reviewed 

for abuse of discretion.” Pulaski & Middleman, LLC v. 

Google, Inc., 802 F.3d 979, 984 (9th Cir. 2015); see also

Zinser, 253 F.3d at 1186. A district court’s decision 

certifying a class or denying class certification will be 
8 CASTILLO V. BANK OF AMERICA

upheld unless it “identified [or] applied the [in]correct legal 

rule” or its “resolution of the motion resulted from a factual 

finding that was illogical, implausible, or without support in 

inferences that may be drawn from the facts in the record.” 

United States v. Hinkson, 585 F.3d 1247, 1263 (9th Cir. 

2009) (en banc). Moreover, a district court’s class 

certification decision may be affirmed on any ground 

supported by the record. Hanon v. Dataproducts Corp., 

976 F.2d 497, 508 (9th Cir. 1992).

III

A. Commonality

“The requirement of ‘commonality’ means that the class 

members’ claims ‘must depend upon a common contention’ 

and that the ‘common contention, moreover, must be of such 

a nature that it is capable of classwide resolution—which 

means that determination of its truth or falsity will resolve 

an issue that is central to the validity of each one of the 

claims in one stroke.’” Vaquero v. Ashley Furniture Indus., 

Inc. 824 F.3d 1150, 1153 (9th Cir. 2016) (quoting Wal-Mart 

Stores, Inc. v. Dukes, 564 U.S. 338, 350 (2011)). Even a 

single common question of law or fact that resolves a central 

issue will be sufficient to satisfy this mandatory requirement 

for all class actions. Id. at 359.

In its response, BOA argues that the district court 

improperly found commonality, and that the district court’s 

decision not to certify the class should be affirmed on that 

alternative ground. BOA contends that there are no common 

questions because the proposed class’s claim involves two 

separate pay policies, over two different time periods, which 

raise separate questions of liability.
CASTILLO V. BANK OF AMERICA 9

But Castillo counters that “each policy applied uniformly 

to all putative class members employed during the period in 

which the policy was in effect.” So, all putative class 

members were subject to one of the two policies for 

calculating overtime wages during the two periods that they 

were in effect. The alleged defect, that “BOA continued to 

use all hours worked in the divisor,” was “equally applicable 

to all Class Members.” Castillo argues that the differences 

between the policies do not defeat commonality, and she 

relies on the district court’s holding that BOA had not 

provided evidence that its calculation of overtime wages 

“was not universal throughout the California locations.” In 

conclusion, Castillo argues that the question of whether or 

not BOA’s policy for calculating overtime wages using total 

hours worked in the divisor is lawful under California law 

presents a purely legal question that is clearly capable of 

class wide resolution.

We agree with Castillo’s interpretation. Here, Castillo’s 

overtime-wage claim presents at least one common question 

central to her claim: whether BOA’s policy of calculating 

overtime wages by using total hours worked in the divisor is 

lawful.

Although there are differences between the two policy 

periods, a common question remains regarding the 

lawfulness of BOA’s using total hours worked in the divisor. 

It is true that BOA may have used different inputs, and the 

policies may have applied differently because of different 

employees’ various fact situations during two different time 

periods. But a common legal question exists central to 

determining liability.

We agree with the district court’s conclusion that “[a]t 

least as to commonality, Plaintiff has shown that whether 
10 CASTILLO V. BANK OF AMERICA

Defendant’s formula was unlawful is a common question 

that can be answered on a classwide basis.”

B. Typicality

“The typicality prerequisite of Rule 23(a) is fulfilled if 

‘the claims or defenses of the representative parties are 

typical of the claims or defenses of the class.’” Hanlon v. 

Chrysler Corp., 150 F.3d 1011, 1020 (9th Cir. 1998) 

(quoting FRCP 23(a)(3)), overruled on other grounds by 

Dukes, 564 U.S. at 338). “Under the rule’s permissive 

standards, representative claims are ‘typical’ if they are 

reasonably co-extensive with those of absent class members; 

they need not be substantially identical.” Id.

In its decision, the district court decided that Castillo’s 

claims were typical of the class. The district court held that 

the submission of the expert report was improper. But the 

court held that “regardless of the improper filing, Plaintiff 

had already established standing to assert this claim.” The 

district court noted that Castillo had included evidence in her 

motion regarding her typicality in this regard, “i.e., that 

Plaintiff received a bonus and worked overtime in the same 

pay periods.” The court held that this demonstrated 

“[p]laintiff was subject to Defendant’s policies regarding its 

inclusion of bonuses in the regular rate of pay for purposes 

of calculating overtime and suffered injury therefrom.”

In its response, BOA argues that Castillo’s claims were 

not typical of the proposed class. BOA also argues that 

Castillo did not properly provide evidence of typicality, 

including that Castillo improperly filed a Supplemental 

Expert Report. Finally, BOA argues that even if Castillo had 

shown she had experienced an injury under the 2016 policy, 

she did not suffer any injury under the 2017 policy.
CASTILLO V. BANK OF AMERICA 11

We conclude that the district court properly found that 

Castillo established typicality. The district court excluded 

the improperly submitted Supplemental Expert Report and 

did not consider it for purposes of its decision. Instead, the 

district court found that Castillo submitted evidence showing 

typicality among her claims and the claims of other class 

members. Castillo has shown that she “was subject to 

Defendant’s policies regarding its inclusion of bonuses in the 

regular rate of pay for purposes of calculating overtime and 

suffered injury therefrom.”

Although there are differences between the two policies, 

the evidence demonstrated that Castillo was subject to 

BOA’s policies and suffered injuries. Castillo’s claims arise 

from the same allegedly unlawful policy of using total hours 

worked in the divisor. For this reason, Castillo’s claims are 

“reasonably co-extensive” with the putative class members, 

and so Castillo has satisfied the requirement of typicality.

C. Predominance

“Under Rule 23(b)(3), a plaintiff must demonstrate the 

superiority of maintaining a class action and show ‘that the 

questions of law or fact common to class members 

predominate over any questions affecting only individual 

members.’” Mazza v. Am. Honda Motor Co., Inc., 666 F.3d 

581, 596 (9th Cir. 2012) (quoting FRCP 23(b)(3)). “[T]he 

focus of the predominance inquiry” is whether “a proposed 

class is ‘sufficiently cohesive to warrant adjudication by 

representation.’” Amgen Inc. v. Conn. Ret. Plans & Tr. 

Funds, 568 U.S. 455, 469 (2013) (quoting Amchem Prods., 

Inc. v. Windsor, 521 U.S. 591, 623 (1997)). But the rule 

“does not require a plaintiff seeking class certification to 

prove that each element of their claim is susceptible to 

classwide proof,” so long as one or more common questions 

predominate. Id. (alterations and internal quotations marks 
12 CASTILLO V. BANK OF AMERICA

omitted); see also Tyson Foods, Inc. v. Bouaphakeo, 136 S. 

Ct. 1036, 1045 (2016).

Individual differences in calculating the amount of 

damages will not defeat class certification where common 

issues otherwise predominate. Vaquero, 824 F.3d at 1155. 

However, “[i]f the plaintiffs cannot prove that damages 

resulted from the defendant’s conduct, then the plaintiffs 

cannot establish predominance.” Id. at 1154. This general 

rule goes to the crux of the issue on appeal here.

To ensure that common questions predominate over 

individual ones, the court must “ensure that the class is not 

defined so broadly as to include a great number of members 

who for some reason could not have been harmed by the 

defendant’s allegedly unlawful conduct.” Torres v. Mercer 

Canyons Inc., 835 F.3d 1125, 1138 (9th Cir. 2016) (citation 

omitted). If many class members have no claim whatsoever 

because they “were never exposed to the challenged conduct 

to begin with,” the class does not satisfy Rule 23(b)(3). Id.

at 1136; see also Moore v. Apple Inc., 309 F.R.D. 532, 542 

(N.D. Cal. 2015) (“The inclusion of class members whom, 

by definition, could not have been injured is . . . indicative 

of the individualized inquiries that would be necessary to 

determine whether a class member has suffered any injury in 

the first place.”).

BOA contends that Castillo has not established 

predominance because she has sought to certify a class that 

would require highly individualized inquiries to determine 

whether class members have suffered an injury in the first 

place. Although Castillo contends that Alvarado, 411 P.3d 

at 528 establishes liability, making all of the alleged 

individualized inquiries mere questions of damages (and not 

liability), BOA has persuasively argued that Castillo has not 

properly established predominance. Those employees who 
CASTILLO V. BANK OF AMERICA 13

did not work overtime or did not earn a bonus during the 

same period in 2016 or 2017 can have no claim for 

compensation based on an erroneous method of overtimerate calculation.

Castillo and BOA disagree over the importance of 

Alvarado. BOA notes, correctly, that Alvarado says nothing 

about class certification or predominance (under Rule 23 or 

otherwise). But Alvarado is not irrelevant. Rather, Alvarado 

could be an important part of Castillo’s case for proving 

BOA’s liability. Alvarado focuses on the proper way to 

calculate the per-hour value of a flat sum bonus earned by 

weekend workers. Alvarado, 411 P.3d at 537; see also id.

at 539 n.6 (“We limit our decision to flat sum bonuses 

comparable to the attendance bonus at issue here.”). 

Alvarado arose from allegations by employees that Dart was 

improperly calculating “attendance bonuses.” Id. at 530. As 

part of the challenged calculation, Dart would use total hours 

(including overtime hours) in the divisor. Id. at 543.

In its opinion, the Supreme Court of California held that 

this method was improper under California Law. Id. The 

Supreme Court of California held that the proper method of 

calculating these bonuses under California law is to use only 

non-overtime hours in the divisor. Id. at 544.

But while Alvarado could bear on the lawfulness of 

BOA’s use of total hours worked in the divisor of its 

overtime formulas, it is not sufficient to establish 

predominance where a large portion of the proposed class 

either (1) did not work overtime or did not receive a bonus 

in the same period, and thus could not have been exposed to 

BOA’s overtime formulas in the first place; or (2) if they 

were exposed to a formula, they were not underpaid and thus 

were not injured. Alvarado does not allow Castillo to 

demonstrate that the court could decide, on a classwide 
14 CASTILLO V. BANK OF AMERICA

basis, issues of liability for all class members. Instead, 

determining liability for all class members would require 

complicated individualized inquiries. Although this method 

of calculation has been deemed improper, the use of the 

method to calculate overtime wages is not evidence of harm 

in every instance to all employees, for those who did not 

work overtime or receive a bonus in the same period, as well 

as those who were overpaid for it have no actual injury and 

hence have no claim.

Castillo’s interpretation of Vaquero is also flawed. 

Vaquero, 824 F.3d at 1154. It is true that Vaquero stands for 

the proposition that individualized damages calculations do 

not defeat predominance. Id. But this does not rebut BOA’s 

argument that the question of whether the putative class 

members were ever “subject to [BOA’s] overtime 

calculation policy and ever underpaid as a result goes to 

liability rather than damages.”

Vaquero involved a question of whether sales employees 

were paid for non-sales work. Id. at 1152. This question 

could be uniformly resolved. Id. If the defendant did not 

pay for non-sales work, the remaining question of how much

should have been paid was a damages question which would 

not defeat predominance. Id. at 1155.

Tyson Foods is also instructive. Tyson Foods held that a 

plaintiff can show that representative evidence “is a 

permissible method of proving classwide liability” if “each 

class member could have relied on that sample to establish 

liability if he or she had brought an individual action,” and 

the representative evidence “could have sustained a 

reasonable jury finding” as to a key issue of liability. 136 S. 

Ct. at 1046–47. In Tyson Foods, employees sued Tyson 

Foods for a policy of not paying them for time spent 

“donning and doffing” protective gear. Id. at 1042. The 
CASTILLO V. BANK OF AMERICA 15

policy alone was not enough to establish liability, though all 

employees were exposed to it. Id. at 1046. Rather, class 

member had to demonstrate that each of them had worked 

more than forty hours in a week to show they were owed 

wages for time spent donning and doffing and that Tyson 

Foods was liable due to the injury caused by the policy. Id.

To determine liability would have required 

individualized inquiries, like in this case. But in Tyson 

Foods the plaintiffs overcame this by submitting 

representative evidence of the hours class members worked. 

Id. at 1046. This common method of proof allowed the 

plaintiffs to establish Tyson Foods’ “classwide liability.” Id. 

Later, damages could be decided individually.

This case differs from Tyson Foods because Castillo 

cannot provide a common method of proof to establish 

BOA’s classwide liability. Unlike in Tyson Foods, here 

there is no common proof of liability, because a large portion 

of the proposed class was never exposed to the challenged 

formulas or was not underpaid, and thus could not have been 

injured by those formulas in the first place. The holding in 

Tyson Foods highlights Castillo’s disagreement with the 

holding of the district court. Castillo contends that the 

district court erred by considering BOA’s “predominance 

attack” to be a question of liability, and not damages. This 

is wrong. The issue is not that Castillo is unable to prove the 

extent of the damages suffered by each individual plaintiff 

at this stage. Instead, it is that Castillo has been unable to 

provide a common method of proving the fact of injury and 

any liability. Unlike in Tyson Foods, proof of liability in this 

case would require highly individualized inquiries. But 

Castillo has provided no common method of proof, or 

representative evidence of proving classwide liability on 

which each employee could have relied. Castillo has sought 
16 CASTILLO V. BANK OF AMERICA

to certify a class but cannot show that questions of law or 

fact common to class members predominate.

Castillo’s misunderstanding of Vaquero and Tyson 

Foods lies at the heart of the issue in this case. Put simply, 

Castillo has sought to certify a class that fails predominance, 

because many of its members were never exposed to the 

challenged formulas or, if they were, were never injured by 

them. Some of the putative class members were (1) not 

exposed to one or both overtime policies, (2) paid adequately 

by one or both overtime polices, or even (3) overpaid by one 

or both of the overtime policies.

When attempting to certify the class, Castillo sought to 

add every call center employee who worked during the class 

period. She did not filter the putative class members to 

exclude those who were never exposed to either policy.3 So, 

the instant case is unlike cases involving non-payment of 

minimum wages, for instance, where by not being paid 

minimum wages, all putative class members who were not 

paid minimum wages suffered an injury. Instead, this case 

raises complicated questions of who was ever exposed to one 

or both policies, and whether those who were exposed were 

harmed in a way giving rise to liability. See, e.g., Torres, 

835 F.3d at 1138 (“In sum, pursuant to Rule 23, the court’s 

task at certification is to ensure that the class is not defined 

so broadly as to include a great number of members who for 

3 In fact, a bank expert estimated that roughly 35.2% of putative 

class members employed by BOA before January 2017 either never 

received an incentive payment, or never worked overtime during a period 

for which they received a bonus. Further, BOA has estimated that around 

41.7% of those in the Bank’s sample never received a bonus or never 

worked overtime during a period for which they received a bonus. A 

large portion of the proposed class was therefore never exposed to the 

challenged policy.
CASTILLO V. BANK OF AMERICA 17

some reason could not have been harmed by the defendant’s 

allegedly unlawful conduct.”).

Castillo has not provided a common method of proof to 

determine liability and has not rebutted evidence that many 

of the class members were not affected by BOA’s overtime 

policies. For these reasons, Castillo has not established 

predominance.

Also, Castillo’s arguments regarding an alleged 

“negation” defense by BOA are misplaced. Plaintiff cites 

several cases rejecting employer attempts to “average” out 

underpayment in one period with over payment in another. 

Armenta v. Osmose, Inc., 135 Cal. App. 4th 314, 319 (Cal. 

Ct. App. 2005); Ferrell v. ConocoPhillips Pipe Line Co., 

2010 WL 1946896, at *8 (C.D. Cal. May 12, 2010); Morse 

v. ServiceMaster Global Holdings Inc., 2011 WL 2470252, 

at *3–4 (N.D. Cal. June 21, 2011). But the issue is not 

whether BOA can “average” out previous underpayment by 

later overpayment. Rather, BOA gives the following 

example:

For example, if the Bank’s calculation of 

overtime wages for one period resulted in a 

“net overpayment” of overtime to an 

employee for that period, then that overall 

overpayment “offsets” any purported dilution 

or underpayment within that particular 

period’s overtime calculation. And because 

of that net overpayment for that period, the 

Bank never incurred liability for an 

underpayment.

BOA does not argue that it can “negate” underpayment 

from prior periods with overpayment in later periods. 

Instead, BOA argues that because of the varying facts 
18 CASTILLO V. BANK OF AMERICA

underlying the calculation, it is possible that employees 

could have been underpaid for sub-parts of a period but 

overpaid overall throughout the period. BOA does not argue 

that it can “negate” past underpayment with later 

overpayment, but that total overpayment “negates” 

underpayment within the same period. This feature of the 

policy—allowing employees to be ostensibly underpaid for 

part of a pay period without ultimately incurring harm—

further complicates and individualizes the calculation 

needed to determine liability.

IV

For the above reasons, we affirm the holding of the 

district court denying class certification.

AFFIRMED.