Exhibit 99.1
MONTHLY SERVICER'S CERTIFICATE
CARMAX BUSINESS SERVICES, LLC
CARMAX AUTO OWNER TRUST
SERIES 2021-3
Collection Period07/01/25-07/31/25
Determination Date8/11/2025
Distribution Date8/15/2025
Additional information, including defined terms, can be found in the prospectus on the SEC's EDGAR system (http://www.sec.gov) under File No. 333-228379-11.




Pool Balance
1.Pool Balance on the close of the last day of the preceding Collection Period$208,212,930.50 
2.Collections allocable to Principal$15,499,371.29 
3.Purchase Amount allocable to Principal$0.00 
4.Defaulted Receivables$814,691.51 
5.Pool Balance on the close of the last day of the related Collection Period$191,898,867.70 
(Ln1 - Ln2 - Ln3 - Ln4)
6.Total number of Receivables outstanding on the close of the last day of the related Collection Period32,768 
7.Initial Pool Balance$1,754,385,994.70 
Beginning of PeriodEnd of Period
8.Note Balances
a. Class A-1 Note Balance
$0.00 $0.00 
b. Class A-2a Note Balance$0.00 $0.00 
c. Class A-2b Floating Rate Note Balance$0.00 $0.00 
d. Class A-3 Note Balance$0.00 $0.00 
e. Class A-4 Note Balance$106,456,965.51 $90,142,902.71 
f. Class B Note Balance$27,190,000.00 $27,190,000.00 
g. Class C Note Balance$47,370,000.00 $47,370,000.00 
h. Class D Note Balance$22,810,000.00 $22,810,000.00 
i. Note Balance (sum a - h)$203,826,965.51 $187,512,902.71 
9.Pool Factors
a. Class A-1 Note Pool Factor0.0000000 0.0000000 
b. Class A-2a Note Pool Factor0.0000000 0.0000000 
c. Class A-2b Floating Rate Note Pool Factor0.0000000 0.0000000 
d. Class A-3 Note Pool Factor0.0000000 0.0000000 
e. Class A-4 Note Pool Factor0.7429476 0.6290942 
f. Class B Note Pool Factor1.0000000 1.0000000 
g. Class C Note Pool Factor1.0000000 1.0000000 
h. Class D Note Pool Factor1.0000000 1.0000000 
i. Note Pool Factor0.1164726 0.1071502 
10.Overcollateralization Target Amount$4,385,964.99 
11.Current overcollateralization amount (Pool Balance - Note Balance)$4,385,964.99 
12.Weighted Average Coupon9.15 %
13.Weighted Average Original Termmonths68.60 
14.Weighted Average Remaining Termmonths19.09 
15.Applicable reference rate for the interest period ending 8/14/2025N/A
16.Note Rate applicable to the Class A-2b notes for the interest period ending 8/14/2025N/A
Collections
17.Finance Charges:
a. Collections allocable to Finance Charge$1,652,049.41 
b. Liquidation Proceeds allocable to Finance Charge$4,053.35 
c. Purchase Amount allocable to Finance Charge$0.00 
d. Available Finance Charge Collections (sum a - c)$1,656,102.76 
18.Principal:
a. Collections allocable to Principal$15,499,371.29 
b. Liquidation Proceeds allocable to Principal$397,074.73 
c. Purchase Amount allocable to Principal$0.00 
d. Available Principal Collections (sum a - c)$15,896,446.02 
19.Total Finance Charge and Principal Collections (17d + 18d)$17,552,548.78 
20.Interest Income from Collection Account$53,038.13 
21.Simple Interest Advances$0.00 
22.Available Collections (Ln19 + 20 + 21)$17,605,586.91 



Available Funds
23.Available Collections$17,605,586.91 
24.Reserve Account Draw Amount$0.00 
25.Available Funds$17,605,586.91 
Application of Available Funds
26.Servicing Fee0.15 %
a. Monthly Servicing Fee$173,510.78 
b. Amount Unpaid from Prior Months$0.00 
c. Amount Paid$173,510.78 
d. Shortfall Amount (a + b - c)$0.00 
27.Unreimbursed Servicer Advances$0.00 
28.Successor Servicer and Asset Representations Reviewer Unpaid Expenses and Indemnity Amounts
a. Successor Servicer Unpaid Transition Expenses and Indemnity Amounts (Capped at $175,000 annually)$0.00 
b. Successor Servicer Amount Paid$0.00 
c. Successor Servicer Shortfall Amount (a - b)$0.00 
d. Asset Representations Reviewer Fees, Expenses and Indemnity Amounts (Capped at $175,000 annually)$0.00 
e. Asset Representations Reviewer Amount Paid$0.00 
f. Asset Representations Reviewer Shortfall Amount (d - e)$0.00 
29.Class A Noteholder Interest Amounts
a. Class A-1 Monthly Interest$0.00 
b. Additional Note Interest related to Class A-1 Monthly Interest$0.00 
c. Interest Due on Additional Note Interest related to Class A-1 Monthly Interest$0.00 
d. Total Class A-1 Note Interest (sum a - c)$0.00 
e. Class A-2a Monthly Interest$— 
f. Additional Note Interest related to Class A-2a Monthly Interest$0.00 
g. Interest Due on Additional Note Interest related to Class A-2a Monthly Interest$0.00 
h. Total Class A-2a Note Interest (sum e - g)$— 
i. Class A-2b Monthly Interest$— 
j. Additional Note Interest related to Class A-2b Monthly Interest$0.00 
k. Interest Due on Additional Note Interest related to Class A-2b Monthly Interest$0.00 
l. Total Class A-2b Note Interest (sum i - k)$— 
m. Class A-3 Monthly Interest$— 
n. Additional Note Interest related to Class A-3 Monthly Interest$0.00 
o. Interest Due on Additional Note Interest related to Class A-3 Monthly Interest$0.00 
p. Total Class A-3 Note Interest (sum m - o)$— 
q. Class A-4 Monthly Interest$65,648.46 
r. Additional Note Interest related to Class A-4 Monthly Interest$0.00 
r. Additional Note Interest related to Class A-4 Monthly Interest$0.00 
t. Total Class A-4 Note Interest (sum q - s)$65,648.46 
30.Priority Principal Distributable Amount$0.00 
31.Class B Noteholder Interest Amount
a. Class B Monthly Interest$22,658.33 
b. Additional Note Interest related to Class B Monthly Interest$0.00 
c. Interest Due on Additional Note Interest related to Class B Monthly Interest$0.00 
d. Total Class B Note Interest (sum a - c)$22,658.33 
32.Secondary Principal Distributable Amount$0.00 
33.Class C Noteholder Interest Amount
a. Class C Monthly Interest$49,343.75 
b. Additional Note Interest related to Class C Monthly Interest$0.00 
c. Interest Due on Additional Note Interest related to Class C Monthly Interest$0.00 
d. Total Class C Note Interest (sum a - c)$49,343.75 
34.Tertiary Principal Distributable Amount$0.00 
35.Class D Noteholder Interest Amount
a. Class D Monthly Interest$28,512.50 
b. Additional Note Interest related to Class D Monthly Interest$0.00 
c. Interest Due on Additional Note Interest related to Class D Monthly Interest$0.00 
d. Total Class D Note Interest (sum a - c)$28,512.50 



36.Quaternary Principal Distributable Amount$11,928,097.81 
37.Required Payment Amount (Ln 26 + Ln 28 + (sum of Ln 29 through Ln 36))$12,267,771.63 
38.Reserve Account Deficiency$0.00 
39.Regular Principal Distributable Amount$4,385,964.99 
40.Remaining Unpaid Servicer Transition Expenses and Additional Servicing Fees, if any$0.00 
41.Remaining Unpaid Trustee and Asset Representations Reviewer Fees, Expenses and Indemnity Amounts, if any
a. Remaining Unpaid Trustee Fees, Expenses and Indemnity Amounts$0.00 
b. Remaining Unpaid Asset Representations Reviewer Fees, Expenses and Indemnity Amounts$0.00 
42.Remaining Unpaid Successor Servicer Indemnity Amounts, if any$0.00 
Collection Account Activity0.15 %
43.Deposits
a. Total Daily Deposits of Finance Charge Collections$1,656,102.76 
b. Total Daily Deposits of Principal Collections$15,896,446.02 
c. Withdrawal from Reserve Account$0.00 
d. Interest Income$53,038.13 
e. Total Deposits to Collection Account (sum a - d)$17,605,586.91 
44.Withdrawals
a. Servicing Fee and Unreimbursed Servicer Advances$173,510.78 
b. Successor Servicer Transition Expenses and Indemnity Amounts$0.00 
c. Deposit to Note Payment Account for Monthly Note Interest/Principal$16,480,225.84 
d. Deposit to Reserve Account$0.00 
e. Excess Collections (Deposit to Certificate Payment Account for payment to Certificateholder)$951,850.29 
f. Total Withdrawals from Collection Account (sum a - e)$17,605,586.91 
Note Payment Account Activity
45.Deposits
a. Class A-1 Interest Distribution$0.00 
b. Class A-2a Interest Distribution$— 
c. Class A-2b Interest Distribution$— 
d. Class A-3 Interest Distribution$— 
e. Class A-4 Interest Distribution$65,648.46 
f. Class B Interest Distribution$22,658.33 
g. Class C Interest Distribution$49,343.75 
h. Class D Interest Distribution$28,512.50 
i. Class A-1 Principal Distribution$0.00 
j. Class A-2a Principal Distribution$0.00 
k. Class A-2b Principal Distribution$0.00 
l. Class A-3 Principal Distribution$0.00 
m. Class A-4 Principal Distribution$16,314,062.80 
n. Class B Principal Distribution$0.00 
o. Class C Principal Distribution$0.00 
p. Class D Principal Distribution$0.00 
q. Total Deposits to Note Payment Account (sum a - p)$16,480,225.84 
46.Withdrawals
a. Class A-1 Distribution$0.00 
b. Class A-2a Distribution$0.00 
c. Class A-2b Distribution$0.00 
d. Class A-3 Distribution$0.00 
e. Class A-4 Distribution$16,379,711.26 
f. Class B Distribution$22,658.33 
g. Class C Distribution$49,343.75 
h. Class D Distribution$28,512.50 
i. Total Withdrawals from Note Payment Account (sum a - h)$16,480,225.84 



Certificate Payment Account Activity
47.Deposits to Certificate Payment Account from Excess Collections$951,850.29 
48.Withdrawals from Certificate Payment Account for Certificateholder Distribution$951,850.29 
Required Reserve Account Amount0.15 %
49.Required Reserve Account Amount (1.00% of Initial Pool Balance)$4,385,964.99 
Reserve Account Reconciliation
50.Beginning Balance (as of end of preceding Distribution Date)$4,385,964.99 
51.Investment Earnings$15,639.19 
52.Reserve Account Draw Amount$0.00 
53.Reserve Account Amount (Ln 50 + Ln 51 - Ln 52)$4,401,604.18 
54.Deposit from Available Funds (Ln 44d)$0.00 
55.If Reserve Account Balance exceeds Required Reserve Account Amount, payment to
a. the Note Payment Account for the payment of principal to the extent of any unfunded Regular Principal Distribution Amount; and$0.00 
b. any Successor Servicer for the payment of any unfunded Transition Costs and Additional Servicing Fee$0.00 
56.Payment to Depositor if Reserve Account Balance exceeds Required Reserve Account Amount and to the extent no unfunded amounts described in Ln 55 exist$15,639.19 
57.Ending Balance (Ln53 + Ln54 - Ln55 - Ln56)$4,385,964.99 
58.Reserve Account Deficiency (Ln50 - Ln57)$0.00 
Instructions to the Trustee
59.Amount to be deposited from the Reserve Account into the Collection Account$0.00 
60.Amount to be paid to Servicer from the Collection Account$173,510.78 
61.Amount to be deposited from the Collection Account into the Note Payment Account$16,480,225.84 
62.Amount to be deposited from the Collection Account into the Certificate Payment Account$951,850.29 
63.Amount to be deposited from the Collection Account into the Reserve Account$0.00 
64.Amount to be deposited from the Reserve Account, if Reserve Account Balance exceeds Required Reserve Account Amount, into
a. the Note Payment Account for any unfunded Regular Principal Distributable Amount$0.00 
b. the Depositor, if no unfunded Regular Principal distributable amount exists$15,639.19 
65.Amount to be paid to Class A-1 Noteholders from the Note Payment Account$0.00 
66.Amount to be paid to Class A-2a Noteholders from the Note Payment Account$0.00 
67.Amount to be paid to Class A-2b Noteholders from the Note Payment Account$0.00 
68.Amount to be paid to Class A-3 Noteholders from the Note Payment Account$0.00 
69.Amount to be paid to Class A-4 Noteholders from the Note Payment Account$16,379,711.26 
70.Amount to be paid to Class B Noteholders from the Note Payment Account$22,658.33 
71.Amount to be paid to Class C Noteholders from the Note Payment Account$49,343.75 
72.Amount to be paid to Class D Noteholders from the Note Payment Account$28,512.50 
73.Amount to be paid to Certificateholders from the Certificate Payment Account with respect to Excess Collections$951,850.29 



Delinquency Activity
Number of LoansPrincipal Balance
74.Delinquency Analysis
a. 31 to 60 days past due1,462$13,420,710.14 
b. 61 to 90 days past due787$7,900,575.36 
c. 91 to 120 days past due140$1,323,546.32 
d. 121 or more days past due0$0.00 
e. Total Past Due (sum a - d)2,389$22,644,831.82 
f. Delinquent Loans as a percentage of end of period Pool Balance (Ln 74e / Ln 5)11.8004 %
75.Has a Delinquency Trigger Event occurred?No
Loss Activity
Number of LoansPrincipal Balance
76.Defaulted Receivables (charge-offs)97$814,691.51 
77.Recoveries262$401,128.08 
78.Net Losses (Ln 76 - Ln 77)$413,563.43 
79.Ratio of Net Losses to Beginning of Period Pool Balance (Ln 78 / Ln 1)0.1986 %
Cumulative Loss Activity
Number of LoansPrincipal Balance
80.Defaulted Receivables (charge-offs)5,132$71,471,513.80 
81.Recoveries4,291$33,718,207.02 
82.Cumulative Net Losses (Ln 80 - Ln 81)$37,753,306.78 
83.Ratio of Cumulative Net Losses to Initial Pool Balance (Ln 82 / Ln 7)2.1519 %
84.Average Net Loss on Defaulted Receivables$7,356.45 
Other Servicing Information
85.Principal Balance of Receivables extended during the Collection Period$3,801,245.93 
86.Pool Balance on the close of the last day of the preceding Collection Period$208,212,930.50 
87.Ratio of extensions to pool balance (Ln 85 / Ln 86)1.83 %




IN WITNESS WHEREOF, the undersigned has duly executed this certificate on August 11, 2025.
 
CARMAX BUSINESS SERVICES, LLC
 
As Servicer
By:/s/ Greg Dostich
Name:Greg Dostich
Title:Vice President and Treasurer