                 FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT


IGOR ZAVALIN,                             No. 13-35276
                Plaintiff-Appellant,
                                            D.C. No.
                v.                     3:12-cv-00114-MO

CAROLYN W. COLVIN,
            Defendant-Appellee.            OPINION


     Appeal from the United States District Court
              for the District of Oregon
    Michael W. Mosman, District Judge, Presiding

               Argued and Submitted
         October 10, 2014—Portland, Oregon

                Filed February 20, 2015

     Before: Ronald M. Gould, Morgan Christen,
      and Jacqueline H. Nguyen, Circuit Judges.

                Opinion by Judge Nguyen
2                      ZAVALIN V. COLVIN

                           SUMMARY*


                          Social Security

    The panel reversed the district court’s judgment affirming
the Social Security Commissioner’s denial of Supplemental
Security Income disability benefits, and remanded for further
proceedings.

    The administrative law judge (“ALJ”) found that the
claimant retained the residual functional capacity to perform
simple, routine, or repetitive tasks; and concluded that the
claimant was not disabled because he was able to perform
two occupations, cashier and surveillance system monitor,
which required the ability to perform Level 3 Reasoning.
Level 3 Reasoning on the Department of Labor’s General
Education Development scale is defined as the ability to
follow written, oral, or diagrammatic instructions and to deal
with problems involving several variables from a
standardized situation.

    The panel held that there was an apparent conflict
between claimant’s limitation to simple, routine, or repetitive
tasks, on the one hand, and the demands of Level 3
Reasoning, on the other hand. The panel further held that
because the ALJ failed to recognize this inconsistency, she
did not ask the vocational expert to explain why a person with
claimant’s limitations could nevertheless meet the demand of
Level 3 Reasoning. The panel concluded that the ALJ erred
in failing to reconcile this apparent conflict, and that the error
was not harmless.

    *
   This summary constitutes no part of the opinion of the court. It has
been prepared by court staff for the convenience of the reader.
                    ZAVALIN V. COLVIN                        3

                         COUNSEL

Brandon Williams (argued), Merrill Schneider, Schneider,
Kerr & Gibney Law Offices, Portland, Oregon, for
Plaintiff-Appellant.

Terrye E. Shea (argued), Assistant Regional Counsel, Office
of the General Counsel, and David Morado, Regional Chief
Counsel, Region X, Social Security Administration, Seattle,
Washington; Kelly A. Zusman, Assistant United States
Attorney, and S. Amanda Marshall, United States Attorney,
United States Attorneys’ Office, Portland, Oregon, for
Defendant-Appellee.


                         OPINION

NGUYEN, Circuit Judge:

    Igor Zavalin appeals the district court’s judgment
affirming the Social Security Commissioner’s denial of
Supplemental Security Income disability benefits. The
administrative law judge (“ALJ”) found that Zavalin retains
the residual functional capacity to perform simple, routine, or
repetitive tasks. The ALJ further concluded that Zavalin is
not disabled because he is still able to perform two
occupations, namely, cashier and surveillance system
monitor. Both of these occupations require the ability to
perform Level 3 Reasoning on the Department of Labor’s
General Education Development scale, which is defined as
the ability to follow written, oral, or diagrammatic
instructions and to deal with problems involving several
variables from a standardized situation. We hold that there is
an apparent conflict between Zavalin’s limitation to simple,
4                    ZAVALIN V. COLVIN

routine, or repetitive tasks, on the one hand, and the demands
of Level 3 Reasoning, on the other hand. This conflict must
be reconciled by the ALJ. Because the ALJ failed to do so,
we remand for further proceedings.

                      BACKGROUND

    Zavalin, who was born in Russia, has suffered from
severe impairments since childhood. His diagnoses include
cerebral palsy, a learning disorder, and a speech impairment
that causes him to speak in a halting manner. He also has a
history of a fracture in his right knee and atrophy of the right
leg, which causes balance problems.

    When Zavalin was 13 years old, he moved with his family
to the United States, and he began receiving Supplemental
Security Income (“SSI”) disability benefits that same year.
Zavalin attended public schools and had an individualized
education program consisting of both special education and
mainstream classes with accommodations for his
impairments, such as extra time so that he could work at his
own pace. He did well, and eventually graduated from high
school with a modified diploma in 2010.

    After Zavalin turned 18 in December 2008, the Social
Security Administration (“SSA”) conducted a
redetermination of his eligibility for benefits under the rules
for determining disability for adults. Zavalin requested
review before an ALJ after the SSA administratively
determined that he was no longer disabled. An ALJ held a
hearing on September 17, 2010, at which she received
testimony from witnesses, including a vocational expert who
testified about potential occupations for Zavalin.
                     ZAVALIN V. COLVIN                        5

    The ALJ asked the vocational expert an extended
hypothetical question in which she described a person with
Zavalin’s limitations, including the limitation that he “can do
simple jobs,” and then inquired whether there are jobs in the
national economy that such a person can do. The expert
opined that a person with such limitations can perform two
representative occupations defined by the Department of
Labor’s Dictionary of Occupational Titles (the “DOT”):
cashier and surveillance system monitor (an employee who
monitors video surveillance footage). The DOT sets forth job
requirements for both positions, including the necessary
reasoning ability, which the DOT measures on a six-level
scale. Both cashier and surveillance system monitor require
Level 3 Reasoning, which is defined as the ability to deal
with problems involving several concrete variables and apply
commonsense understanding to carry out instructions
furnished in written, oral, or diagrammatic form. However,
the ALJ did not ask the vocational expert to explain how a
person who can only “do simple jobs” because of
impairments, including a learning disorder and cerebral palsy,
could meet Level 3 Reasoning’s requirements.

    Following the hearing, the ALJ issued a written decision
on October 28, 2010. The ALJ’s analysis followed the
well-established five-step sequential process for Social
Security and SSI disability determinations. The ALJ skipped
Step One, which asks whether Zavalin is presently working,
because it is not relevant in age-18 disability
redeterminations. At Step Two, the ALJ found that Zavalin
suffers from several severe impairments: cerebral palsy, a
learning disorder, a history of right knee fracture, and atrophy
of the right leg. At Step Three, the ALJ found that Zavalin
does not have an impairment listed in SSA regulations. Step
6                   ZAVALIN V. COLVIN

Four, which determines whether Zavalin could return to a
previous occupation, did not apply.

    At Step Five—the only step at issue on appeal—the ALJ
analyzed whether Zavalin has the capacity to work
notwithstanding his severe impairments. The ALJ first
assessed Zavalin’s capability in light of his impairments.
Based on medical reports from doctors and health care
professionals who had evaluated Zavalin over the years, as
well as Zavalin’s testimony, the ALJ concluded that his
ability is limited to “simple, routine tasks” and “simple,
repetitive tasks.” The ALJ also found that he can use his
arms with some limitations, has balance problems, cannot
climb ladders or ropes, and has a speech impairment. The
ALJ then determined whether there are jobs in the national
economy that Zavalin can perform in light of his limitations,
age, education, and lack of work experience. To make this
determination, she relied on the vocational expert’s testimony
that a person with Zavalin’s limitations can perform cashier
and surveillance system monitor work, and the DOT’s job
descriptions and requirements for these occupations. The
ALJ concluded that Zavalin is not disabled because he is
capable of both identified occupations. In her decision, the
ALJ did not explain whether Zavalin possessed the reasoning
ability required to perform these occupations, given his
residual functional capacity of only simple, routine, or
repetitive work.

    After the SSA Appeals Council denied his request for
review of the ALJ’s decision, Zavalin sought judicial review
in the district court. The district court summarily affirmed.
This appeal followed.
                        ZAVALIN V. COLVIN                                7

     JURISDICTION AND STANDARD OF REVIEW

   We have jurisdiction under 28 U.S.C. § 1291. We review
de novo the district court’s decision. Molina v. Astrue,
674 F.3d 1104, 1110 (9th Cir. 2012). We review the
Commissioner’s disability decision “to determine if it is
supported by substantial evidence in the record as a whole
and whether it is based on proper legal standards.” Nyman v.
Heckler, 779 F.2d 528, 530 (9th Cir. 1986). Even when an
ALJ commits an error of law, we must affirm if the error is
harmless. Molina, 674 F.3d at 1111.

                           DISCUSSION

    Zavalin argues that at Step Five, the ALJ failed to
reconcile an apparent conflict between his residual functional
capacity and the reasoning requirements of the jobs identified
by the ALJ. We agree.

                                    I

                                    A

    We begin with the legal framework for Step Five.1 At
this step, the Commissioner has the burden “to identify
specific jobs existing in substantial numbers in the national
economy that [a] claimant can perform despite [his] identified


 1
    To determine whether or not a claimant is disabled, an ALJ follows a
five-step evaluation. See 20 C.F.R. § 416.920(a)(4). If the ALJ finds that
a claimant is either disabled or not disabled at any step, the ALJ does not
continue on to the next step. Id.; see also Bustamante v. Massanari,
262 F.3d 949, 953–54 (9th Cir. 2001) (discussing the five-step evaluation
in detail).
8                   ZAVALIN V. COLVIN

limitations.” Johnson v. Shalala, 60 F.3d 1428, 1432 (9th
Cir. 1995); see also 20 C.F.R. § 416.920(g). The ALJ first
assesses a claimant’s “residual functional capacity,” defined
as the most that a claimant can do despite “physical and
mental limitations” caused by his impairments and related
symptoms. 20 C.F.R. § 416.945(a)(1). The ALJ then
considers potential occupations that the claimant may be able
to perform. See 20 C.F.R. § 416.966. In making this
determination, the ALJ relies on the DOT, which is the SSA’s
“primary source of reliable job information” regarding jobs
that exist in the national economy. Terry v. Sullivan,
903 F.2d 1273, 1276 (9th Cir. 1990); see also 20 C.F.R.
§§ 416.969, 416.966(d)(1). The DOT describes the
requirements for each listed occupation, including the
necessary General Educational Development (“GED”) levels;
that is, “aspects of education (formal and informal) . . .
required of the worker for satisfactory job performance.”
DOT, App. C, 1991 WL 688702 (4th ed. 1991). The GED
levels includes the reasoning ability required to perform the
job, ranging from Level 1 (which requires the least reasoning
ability) to Level 6 (which requires the most). See id.

    In addition to the DOT, the ALJ relies on the testimony of
vocational experts who testify about specific occupations that
a claimant can perform in light of his residual functional
capacity. 20 C.F.R. § 416.966(e); Valentine v. Comm’r Soc.
Sec. Admin., 574 F.3d 685, 689 (9th Cir. 2009). Finally, to
conclude the Step Five analysis, the ALJ determines
“whether, given the claimant’s [residual functional capacity],
age, education, and work experience, he actually can find
some work in the national economy.” Valentine, 574 F.3d at
689; see also 20 C.F.R. § 416.920(g).
                    ZAVALIN V. COLVIN                       9

    When there is an apparent conflict between the vocational
expert’s testimony and the DOT—for example, expert
testimony that a claimant can perform an occupation
involving DOT requirements that appear more than the
claimant can handle—the ALJ is required to reconcile the
inconsistency. Massachi v. Astrue, 486 F.3d 1149, 1153–54
(9th Cir. 2007). The ALJ must ask the expert to explain the
conflict and “then determine whether the vocational expert’s
explanation for the conflict is reasonable” before relying on
the expert’s testimony to reach a disability determination.
Id.; see also Social Security Ruling 00-4P, 2000 WL
1898704, at *2 (Dec. 4, 2000). The ALJ’s failure to resolve
an apparent inconsistency may leave us with a gap in the
record that precludes us from determining whether the ALJ’s
decision is supported by substantial evidence. See Massachi,
486 F.3d at 1154 (stating that “we cannot determine whether
the ALJ properly relied on [the vocational expert’s]
testimony” due to unresolved occupational evidence).

                              B

    We now turn to Zavalin’s claim that the ALJ erred at Step
Five. Zavalin does not contest the ALJ’s finding that his
residual functional capacity limits him to simple, routine, or
repetitive work. He argues, however, that there is an inherent
inconsistency between his limitation to simple, routine tasks,
and the requirements of Level 3 Reasoning.

    We have not in our circuit addressed this question, and it
is one on which our sister circuits are split. For example, in
Hackett v. Barnhart, the Tenth Circuit held that a claimant’s
limitation to “simple and routine work tasks” is “inconsistent
with the demands of level-three reasoning” because the
plaintiff’s residual functional capacity was more consistent
10                   ZAVALIN V. COLVIN

with Level 2 than Level 3 Reasoning. 395 F.3d 1168, 1176
(10th Cir. 2005). In contrast, with little analysis, the Seventh
and Eighth Circuits rejected the claim that a conflict exists.
See Terry v. Astrue, 580 F.3d 471, 478 (7th Cir. 2009);
Renfrow v. Astrue, 496 F.3d 918, 921 (8th Cir. 2007).
District courts in our circuit that have confronted this issue
are also divided. See, e.g., Adams v. Astrue, No. C 10-2008
DMR, 2011 WL 1833015, at *4 (N.D. Cal. May 13, 2011)
(stating that “there appears to be a conflict between” a
limitation to “simple, repetitive tasks” and Level 3
Reasoning); Wentz v. Astrue, CIV. No. 08-661-PK, 2009 WL
3734104, at *13–15 (D. Or. Nov. 4, 2009) (finding “no
apparent conflict” between a limitation to “simple, routine,
repetitive work” and Level 3).

    Today, we join the Tenth Circuit and hold that there is an
apparent conflict between the residual functional capacity to
perform simple, repetitive tasks, and the demands of Level 3
Reasoning. We find the conflict to be plain when we
consider, side-by-side, the definitions of Level 2 and Level 3
Reasoning:

       LEVEL 2

       Apply commonsense understanding to carry
       out detailed but uninvolved written or oral
       instructions. Deal with problems involving a
       few concrete variables in or from standardized
       situations.

       LEVEL 3

       Apply commonsense understanding to carry
       out instructions furnished in written, oral, or
                    ZAVALIN V. COLVIN                      11

       diagrammatic form. Deal with problems
       involving several concrete variables in or
       from standardized situations.

DOT, App. C, 1991 WL 688702.                        Level 2
Reasoning—applying common sense to carry out detailed but
uncomplicated instructions and dealing with problems
involving a few variables—seems at least as consistent with
Zavalin’s limitation as Level 3 Reasoning, if not more so.
See Hackett, 395 F.3d at 1176 (noting that Level 2 “appears
more consistent” than Level 3 for a claimant limited to
simple, routine tasks). Further, Zavalin’s limitation to
simple, routine tasks is at odds with Level 3’s requirements
because “it may be difficult for a person limited to simple,
repetitive tasks to follow instructions in ‘diagrammatic form’
as such instructions can be abstract.” Adams, 2011 WL
1833015, at *4.

    The Commissioner argues that the DOT’s reasoning
levels correspond only to a person’s level of education and,
therefore, Zavalin is presumptively capable of Level 3
Reasoning because he completed high school. We are
unpersuaded. Contrary to the Commissioner’s claim, the
DOT specifically defines GED reasoning levels to include
“informal” as well as “formal” education that is required for
“satisfactory job performance.” DOT, App. C, 1991 WL
688702. Thus, there is no rigid correlation between reasoning
levels and the amount of education that a claimant has
completed. While Zavalin’s educational background is
relevant, the DOT’s reasoning levels clearly correspond to the
claimant’s ability because they assess whether a person can
“apply” increasingly difficult principles of rational thought
and “deal” with increasingly complicated problems. Id. For
example, Level 1 requires the ability to “carry out simple
12                   ZAVALIN V. COLVIN

one- or two-step instructions,” whereas Level 6 requires the
application of “principles of logical or scientific thinking to
a wide range of intellectual and practical problems.” Id.
Moreover, the Commissioner’s reliance on Zavalin’s
completion of high school ignores the fact that he was in
special education classes, and succeeded in regular classes
only with special accommodations that allowed him to work
at his own pace. Further, while he graduated, Zavalin
received a modified diploma, which is conferred on “students
who have demonstrated the inability to meet the full set of
academic content standards for a high school diploma even
with reasonable modifications and accommodations.” Or.
Admin. R. 581-022-1134(2).

    In sum, because the ALJ failed to recognize an
inconsistency, she did not ask the expert to explain why a
person with Zavalin’s limitation could nevertheless meet the
demands of Level 3 Reasoning. We conclude that the ALJ
erred in failing to reconcile this apparent conflict.

                              II

    Lastly, we address whether the ALJ’s error is harmless.
See Molina, 674 F.3d at 1111 (stating that “we may not
reverse an ALJ’s decision on account of an error that is
harmless”).      In making this determination, we are
“constrained to review the reasons the ALJ asserts” and
“cannot affirm the decision of an agency on a ground that the
agency did not invoke in making its decision.” Stout v.
Comm’r, Soc. Sec. Admin., 454 F.3d 1050, 1054 (9th Cir.
2006) (citations and internal quotation marks omitted). The
parties dispute whether Zavalin’s abilities, such as his success
in school, demonstrate that he is capable of working as a
cashier and surveillance system monitor, such that the ALJ’s
                    ZAVALIN V. COLVIN                     13

error in failing to reconcile any inconsistency would be
harmless.

    We first consider the DOT’s descriptions of these jobs.
A surveillance system monitor is a security employee
responsible for monitoring security cameras in public
transportation terminals. The employee must be able to
“detect crimes or disturbances,” “notify authorities” when
required, while continuing to “maintain surveillance of [the]
location where [the] incident is developing.”            DOT
379.367-010, 1991 WL 673244. A cashier must be able to
compute bills, itemized lists, and tickets showing the amount
due, reconcile the cash register’s tape against cash on hand,
and give cash refunds and issue credit memorandums to
customers for returned merchandise. DOT 211.462-010,
1991 WL 671840.

    The Commissioner relies heavily on Zavalin’s success in
math, which was one of his strengths while in school, and his
use of computers and video games, to argue that he is capable
of performing the identified jobs. However, while the record
shows that Zavalin did well in math, it was in the context of
a special education program. As for his use of the computer
and video games, the ALJ did not rely on this evidence, and
we cannot do so now to find the error harmless. Stout,
454 F.3d at 1054. Even if we were to consider this evidence,
we are not persuaded that it shows Zavalin possesses the
requisite reasoning ability because there is no indication of
the extent or manner of his computer use, or the complexity
of the video games.

    Certainly, Zavalin’s educational successes are not
irrelevant and we agree that he appears capable of performing
some of the duties required in these occupations. However,
14                  ZAVALIN V. COLVIN

other tasks seem neither simple nor routine. As a cashier,
reconciling the cash on hand against the cash register’s tape
and issuing credit memorandums to customers could contain
situational variables that may not be simple or repetitive.
Similarly, a surveillance system monitor may be called upon
to use discretion and judgment in rapidly evolving scenarios,
including deciding when a situation requires the authorities to
be notified, all while continuing to maintain surveillance.

    On this mixed record, “we cannot determine whether
substantial evidence supports the ALJ’s step-five finding that
[Zavalin] could perform [the] work.” Massachi, 486 F.3d at
1154. We therefore conclude that the ALJ’s failure to
reconcile the apparent conflict is not harmless.

                      CONCLUSION

    We reverse and remand to the district court so that it may
remand to the SSA for further proceedings consistent with
this opinion. See Moisa v. Barnhart, 367 F.3d 882, 886 (9th
Cir. 2004). We do not reach the parties’ remaining
arguments.

     REVERSED AND REMANDED.
