<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt"> </P>

<P STYLE="text-align: right; font: 10pt Times New Roman, Times, Serif; margin: 0pt"><B>Exhibit 4.2</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; text-align: right; margin: 0pt"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">SUPPLEMENTAL INDENTURE ESTABLISHING A SERIES OF
NOTES</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">BOOZ ALLEN HAMILTON INC.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">as Issuer</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">and</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">the Subsidiary Guarantors from time to time party
to the Indenture</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">and</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">WILMINGTON TRUST, NATIONAL ASSOCIATION</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">as Trustee</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">____</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">FIRST SUPPLEMENTAL INDENTURE</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">DATED AS OF JUNE 17, 2021</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">____</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">4.000% Senior Notes Due 2029</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">FIRST SUPPLEMENTAL INDENTURE,
dated as of June 17, 2021 (this “<U>Supplemental Indenture</U>”), among Booz Allen Hamilton Inc. (the “<U>Issuer</U>”),
the Subsidiary Guarantors under the Indenture referred to below (the “<U>Subsidiary Guarantors</U>”), and Wilmington Trust,
National Association, as Trustee under the Indenture referred to below.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">W I T N E S S E T H:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">WHEREAS, the Issuer, the Subsidiary
Guarantors and the Trustee, are party to an Indenture, dated as of June 17, 2021 (as amended, supplemented, waived or otherwise modified,
the “<U>Indenture</U>”), relating to the issuance from time to time by the Issuer of Notes;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">WHEREAS, Section 9.1(xiv)
of the Indenture provides that the Issuer may provide for the issuance of Notes of any series as permitted by Section 2.4 therein;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">WHEREAS, in connection with
the issuance of the 2029 Notes (as defined herein), the Issuer has duly authorized the execution and delivery of this Supplemental Indenture
to establish the forms and terms of the 2029 Notes as hereinafter described; and</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">WHEREAS, pursuant to Section
9.1 of the Indenture, the parties hereto are authorized to execute and deliver this Supplemental Indenture to amend the Indenture, without
the consent of any Holder;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">NOW, THEREFORE, in consideration
of the foregoing and for other good and valuable consideration, the receipt of which is hereby acknowledged, the Issuer, the Subsidiary
Guarantors and the Trustee mutually covenant and agree for the benefit of the Holders of the Notes as follows:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">1.       <U>Defined
Terms</U>. As used in this Supplemental Indenture, terms defined in the Indenture or in the preamble or recital hereto are used herein
as so defined. The words “herein,” “hereof” and “hereby” and other words of similar import used in
this Supplemental Indenture refer to this Supplemental Indenture as a whole and not to any particular section hereof.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">2.       <U>Title
of Notes</U>. There shall be a series of Notes of the Issuer designated the 4.000% Senior Notes due 2029 (the “<U>2029 Notes</U>”).</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">3.       <U>Maturity
Date</U>. The final Stated Maturity of the 2029 Notes shall be July 1, 2029.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">4.       <U>Interest
and Interest Rates</U>. Interest on the Outstanding principal amount of the 2029 Notes will accrue at the rate of 4.000% per annum
and will be payable semi-annually in arrears on July 1 and January 1 in each year, commencing on January 1, 2022, to Holders of
record on the immediately preceding June 15 and December 15, respectively (each such June 15 and December 15, a “<U>Regular
Record Date</U>”). Interest on the 2029 Notes will accrue from the most recent date to which interest has been paid or
provided for or, if no interest has been paid, from June 17, 2021, except that interest on any Additional 2029 Notes (as defined
below) issued on or after the first Interest Payment Date will accrue (or will be deemed to have accrued) from the most recent date
to which interest has been paid or duly provided for or, if no interest has been paid on such Additional 2029 Notes, from the
Interest Payment Date immediately preceding the date of issuance of such Additional 2029 Notes (or if the date of issuance of such
Additional 2029 Notes is an Interest Payment Date, from such date of issuance); <U>provided</U> that if any 2029 Note is surrendered
for exchange on or after a record date for an Interest Payment Date that will occur on or after the date of such exchange, interest
on such Note received in exchange thereof will accrue from such Interest Payment Date.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">5.       <U>No
Limitation on Aggregate Principal Amount</U>. The aggregate principal amount of 2029 Notes that may be authenticated and delivered and
Outstanding under the Indenture is not limited. The aggregate principal amount of the 2029 Notes shall initially be $500.0 million.
Subject to the terms of the Indenture, the Issuer may from time to time, without the consent of the Holders, create and issue Additional
Notes having the same terms and conditions as the 2029 Notes in all respects or in all respects except for issue date, issue price and,
if applicable, the first date on which interest accrues and the first payment of interest thereon. Additional Notes issued in this manner
will be consolidated with, and will form a single series with, the 2029 Notes (any such Additional Notes, “<U>Additional 2029 Notes</U>”),
unless otherwise specified for Additional Notes in an applicable Notes Supplemental Indenture, or otherwise designated by the Issuer,
as contemplated by Section 2.4 of the Indenture.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">6.       <U>Redemption</U>.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.75in">(a)       On and after July
1, 2024, the Issuer may redeem the 2029 Notes, at its option, in whole at any time or in part from time to time, upon notice as described
in Section 5.4 of the Indenture, at the following redemption prices (expressed as a percentage of principal amount), plus accrued and
unpaid interest, if any, to (but not including) the Redemption Date (subject to the right of Holders of record on the relevant Regular
Record Date to receive interest due on the relevant Interest Payment Date falling prior to or on the Redemption Date), if redeemed during
the 12-month period commencing on July 1 of the years set forth below:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in"> </P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="border-collapse: collapse; width: 100%; font: 10pt Times New Roman, Times, Serif">
  <TR STYLE="vertical-align: bottom">
    <TD STYLE="font: bold 10pt Times New Roman, Times, Serif; border-bottom: Black 1pt solid">Redemption Period</TD><TD STYLE="font: bold 10pt Times New Roman, Times, Serif; padding-bottom: 1pt"> </TD>
    <TD COLSPAN="2" STYLE="font: bold 10pt Times New Roman, Times, Serif; text-align: center; border-bottom: Black 1pt solid">Price</TD><TD STYLE="padding-bottom: 1pt; font: bold 10pt Times New Roman, Times, Serif"> </TD></TR>
  <TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="width: 87%; font-size: 10pt; text-align: left">2024</TD><TD STYLE="width: 1%; font-size: 10pt"> </TD>
    <TD STYLE="width: 1%; font-size: 10pt; text-align: left"> </TD><TD STYLE="width: 10%; font-size: 10pt; text-align: right">102.000</TD><TD STYLE="width: 1%; font-size: 10pt; text-align: left">%</TD></TR>
  <TR STYLE="vertical-align: bottom; background-color: White">
    <TD STYLE="font-size: 10pt; text-align: left">2025</TD><TD STYLE="font-size: 10pt"> </TD>
    <TD STYLE="font-size: 10pt; text-align: left"> </TD><TD STYLE="font-size: 10pt; text-align: right">101.000</TD><TD STYLE="font-size: 10pt; text-align: left">%</TD></TR>
  <TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="font-size: 10pt; text-align: left">2026 and thereafter</TD><TD STYLE="font-size: 10pt"> </TD>
    <TD STYLE="font-size: 10pt; text-align: left"> </TD><TD STYLE="font-size: 10pt; text-align: right">100.000</TD><TD STYLE="font-size: 10pt; text-align: left">%</TD></TR>
  </TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.75in">(b)       In addition, at
any time prior to July 1, 2024, the Issuer may redeem the 2029 Notes at its option, in whole at any time or in part from time to time,
upon notice as described in Section 5.4 of the Indenture, at a redemption price equal to 100.0% of the principal amount of the 2029 Notes
redeemed plus the Applicable Premium calculated by the Issuer as of the date of the redemption notice, and accrued and unpaid interest,
if any, to (but not including) the applicable Redemption Date (subject to the right of Holders of record on the relevant Regular Record
Date to receive interest due on the relevant interest payment date falling prior to or on the Redemption Date).</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.75in">(c)       Notwithstanding the
foregoing, at any time and from time to time, upon notice as described in Section 5.4 of the Indenture, on or prior to July 1, 2024,
the Issuer may redeem in the aggregate up to 40.0% of the original aggregate principal amount of the 2029 Notes (calculated after giving
effect to any issuance of any Additional 2029 Notes, or any other Additional Notes of the same series as the 2029 Notes) with an amount
equal to the net cash proceeds of one or more Equity Offerings by the Issuer or any direct or indirect parent of the Issuer, to the extent
net cash proceeds thereof are contributed to the common equity capital of the Issuer or used to purchase Capital Stock (other than Disqualified
Stock) of the Issuer from it, at a redemption price (expressed as a percentage of the principal amount thereof) equal to 104.000%, plus
accrued and unpaid interest, if any, to (but not including) the Redemption Date (subject to the right of Holders of record on the relevant
record date to receive interest due on the relevant interest payment date falling prior to or on the Redemption Date); <U>provided</U>,
<U>however</U>, that at least 50.0% of the original aggregate principal amount of the 2029 Notes (calculated after giving effect to any
issuance of any Additional 2029 Notes, or any other Additional Notes of the same series as the 2029 Notes) must remain outstanding after
each such redemption; and <U>provided</U>, <U>further</U>, that such redemption shall occur within 180 days after the date on which any
such Equity Offering is consummated.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in"> </P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.75in">(d)       Notwithstanding
the foregoing, in connection with any tender for or other offer to purchase 2029 Notes, if Holders of not less than 90.0% in aggregate
principal amount of the outstanding 2029 Notes validly tender and do not withdraw such 2029 Notes in such tender or other offer and the
Issuer, or any third party making such a tender or other offer in lieu of the Issuer, purchases all of the 2029 Notes validly tendered
and not withdrawn by such Holders, all of the Holders of the 2029 Notes will be deemed to have consented to such tender or other offer
and accordingly, the Issuer or such third party will have the right upon not less than 10 nor more than 60 days’ prior notice, given
not more than 30 days following such purchase date, to redeem all 2029 Notes that remain outstanding following such purchase at a price
equal to the price offered to each other Holder in such tender offer plus, to the extent not included in the tender or other offer payment,
accrued and unpaid interest, if any, thereon, to, but excluding, the Redemption Date.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.75in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">“<U>Applicable Premium</U>”
means, with respect to any 2029 Note on any applicable Redemption Date, as calculated by the Issuer or on behalf of the Issuer by such
Person as the Issuer shall designate (and the Trustee shall have no duty to calculate or verify the calculations of the same), the greater
of:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">(1)       1.0%
of the then outstanding principal amount of the 2029 Note; and</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">(2)       the
excess, if any, of</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: left; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; text-indent: 0.85in; margin-top: 0pt; margin-right: 0; margin-bottom: 0pt; text-align: left">(a)       the
present value at such Redemption Date calculated as of the date of the applicable redemption notice of (<U>i</U>) the redemption
price of the Note at July 1, 2024 (such redemption price being that described in clause (a) of this Section 6) plus (<U>ii</U>) all
required remaining scheduled interest payments due on the 2029 Note through July 1, 2024 (excluding accrued but unpaid interest to (but
not including) the Redemption Date), computed using a discount rate equal to the Treasury Rate plus 50 basis points; over</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: left; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; text-indent: 0.85in; margin-top: 0pt; margin-right: 0; margin-bottom: 0pt; text-align: left">(b)       the
then outstanding principal amount of the 2029 Note.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.5in; text-align: justify; text-indent: 0.5in"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">“<U>Treasury Rate</U>”
means, with respect to a Redemption Date, the weekly average yield to maturity at the time of computation of United States Treasury securities
with a constant maturity (as compiled and published in the most recent Federal Reserve Statistical Release H.15 (519) that has become
publicly available at least two Business Days prior to the date of the applicable redemption notice (or, if such Statistical Release is
no longer published, any publicly available source of similar market data)) most nearly equal to the period from such Redemption Date
to July 1, 2024, <U>provided</U>, <U>however</U>, that if the period from such Redemption Date to July 1, 2024 is not equal to the constant
maturity of a United States Treasury security for which a weekly average yield is given, the Treasury Rate shall be obtained by linear
interpolation (calculated to the nearest one-twelfth of a year) from the weekly average yields of United States Treasury securities for
which such yields are given, except that if the period from July 1, 2024 to such Redemption Date is less than one year, the weekly average
yield on actually traded United States Treasury securities adjusted to a constant maturity of one year shall be used.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">7.       [Reserved]</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">8.       <U>Form</U>.
The 2029 Notes shall be issued substantially in the form set forth, or referenced, in Article II of the Indenture and Exhibit A attached
to the Indenture, in each case as provided for in Section 2.1 of the Indenture (as such form may be modified in accordance with Section
2.4 of the Indenture).</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">9.       <U>Governing
Law</U>. THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK. <FONT STYLE="text-transform: uppercase">The
Trustee, the Issuer, EACH SUBSIDIARY GUARANTOR, any other obligor upon the Notes, and (by their acceptance of the Notes) the Holders agree
to submit to the jurisdiction of any United States Federal or state court located in the Borough of Manhattan, in the city of New York
in any action or legal proceeding arising out of or relating to this SUPPLEMENTAL Indenture or the transactions contemplated thereby.</FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">10.     <U>Ratification
of Indenture; Supplemental Indentures Part of Indenture</U>. Except as expressly amended hereby, the Indenture is in all respects ratified
and confirmed and all the terms, conditions and provisions thereof shall remain in full force and effect. This Supplemental Indenture
shall form a part of the Indenture for all purposes, and every Holder heretofore or hereafter authenticated and delivered shall be bound
hereby. The Trustee makes no representation or warranty as to the validity or sufficiency of this Supplemental Indenture or as to the
accuracy of the recitals to this Supplemental Indenture.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">11.     <U>Counterparts</U>.
The parties hereto may sign one or more copies of this Supplemental Indenture in counterparts, all of which together shall constitute
one and the same agreement. Delivery of an executed counterpart of a signature page to this Supplemental Indenture by telecopier, facsimile
or other electronic transmission (i.e. a “.pdf” or “.tif”) shall be effective as delivery of a manually executed
counterpart thereof.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in"> </P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">12.     <U>Headings</U>.
The section headings herein are for convenience of reference only and shall not be deemed to alter or affect the meaning or interpretation
of any provisions hereof.</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: left; text-indent: 0.5in">IN WITNESS WHEREOF, the parties
hereto have caused this Supplemental Indenture to be duly executed as of the date first above written.</P>

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  <TD STYLE="padding-left: 10pt; text-indent: -10pt; width: 50%"> </TD>
  <TD STYLE="padding-left: 10pt; text-indent: -10pt; width: 50%">BOOZ ALLEN HAMILTON INC.</TD></TR>
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<TD STYLE="width: 50%"></TD><TD STYLE="width: 3%; text-align: left">By:</TD><TD STYLE="border-bottom: Black 1pt solid; text-align: justify; width: 47%">/s/ Lloyd W.
                                            Howell, Jr.</TD>
</TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" BORDER="0" STYLE="width: 100%; margin-top: 0pt; margin-bottom: 0pt; font: 10pt Times New Roman, Times, Serif">
<TR STYLE="vertical-align: top">
  <TD STYLE="padding-left: 10pt; text-indent: -10pt; width: 53%"> </TD>
  <TD STYLE="padding-left: 10pt; text-indent: -10pt; width: 47%">Name: Lloyd W. Howell, Jr.</TD></TR>

<TR STYLE="vertical-align: top">
  <TD STYLE="padding-left: 10pt; text-indent: -10pt"> </TD>
  <TD STYLE="padding-left: 10pt; text-indent: -10pt">Title: Executive Vice President, Chief Financial Officer and Treasurer</TD></TR>
</TABLE>


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  <TD STYLE="padding-left: 10pt; text-indent: -10pt; width: 50%"> </TD>
  <TD STYLE="padding-left: 10pt; text-indent: -10pt; width: 50%">SUBSIDIARY GUARANTORS</TD></TR>
</TABLE>


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  <TD STYLE="padding-left: 10pt; text-indent: -10pt; width: 50%"> </TD>
  <TD STYLE="padding-left: 10pt; text-indent: -10pt; width: 50%">EGOV HOLDINGS, INC.</TD></TR>
</TABLE>


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<TD STYLE="width: 50%"></TD><TD STYLE="width: 3%; text-align: left">By:<U></U></TD><TD STYLE="border-bottom: Black 1pt solid; text-align: justify; width: 47%">/s/ Laura S. Adams</TD>
</TR></TABLE>

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<TD STYLE="width: 53%"></TD><TD STYLE="width: 5%; text-align: left">Name:</TD><TD STYLE="text-align: justify; width: 42%">Laura S. Adams</TD>
</TR>
<TR STYLE="vertical-align: top; text-align: justify">
<TD></TD><TD STYLE="text-align: left">Title:</TD><TD STYLE="text-align: justify">Treasurer</TD>
</TR></TABLE>

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<TABLE CELLPADDING="0" CELLSPACING="0" BORDER="0" STYLE="width: 100%; margin-top: 0pt; margin-bottom: 0pt; font: 10pt Times New Roman, Times, Serif">
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  <TD STYLE="padding-left: 10pt; text-indent: -10pt; width: 50%"> </TD>
  <TD STYLE="padding-left: 10pt; text-indent: -10pt; width: 50%">AQUILENT, INC.</TD></TR>
</TABLE>


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<TD STYLE="width: 50%"></TD><TD STYLE="width: 3%; text-align: left">By:</TD><TD STYLE="border-bottom: Black 1pt solid; text-align: justify; width: 47%">/s/ Laura S.
                                            Adams</TD>
</TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0; width: 100%"><TR STYLE="vertical-align: top; text-align: justify">
<TD STYLE="width: 53%"></TD><TD STYLE="width: 5%; text-align: left">Name:</TD><TD STYLE="text-align: justify; width: 42%">Laura S. Adams</TD>
</TR>
<TR STYLE="vertical-align: top; text-align: justify">
<TD></TD><TD STYLE="text-align: left">Title:</TD><TD STYLE="text-align: justify">Treasurer</TD>
</TR></TABLE>

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<TABLE CELLPADDING="0" CELLSPACING="0" BORDER="0" STYLE="width: 100%; margin-top: 0pt; margin-bottom: 0pt; font: 10pt Times New Roman, Times, Serif">
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  <TD STYLE="padding-left: 10pt; text-indent: -10pt; width: 50%"> </TD>
  <TD STYLE="padding-left: 10pt; text-indent: -10pt; width: 50%">WILMINGTON TRUST, NATIONAL ASSOCIATION, as Trustee</TD></TR>
</TABLE>


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<TD STYLE="width: 50%"></TD><TD STYLE="width: 3%; text-align: left">By:</TD><TD STYLE="border-bottom: Black 1pt solid; text-align: justify; width: 47%">/s/ Barry D.
                                            Somrock</TD>
</TR></TABLE>

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  <TD STYLE="padding-left: 10pt; text-indent: -10pt; width: 53%"> </TD>
  <TD STYLE="padding-left: 10pt; text-indent: -10pt; width: 47%">Authorized Officer</TD></TR>
</TABLE>


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