# EDGAR Filing Document

**Accession Number:** 0001709682
**File Stem:** 0001709682-26-000031
**Filing Date:** 2026-4
**Character Count:** 4542
**Document Hash:** fac6187cd777d75e8e8c1337086b043f
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001709682-26-000031.hdr.sgml**: 20260429

**ACCESSION NUMBER**: 0001709682-26-000031

**CONFORMED SUBMISSION TYPE**: DEFA14A

**PUBLIC DOCUMENT COUNT**: 3

**FILED AS OF DATE**: 20260429

**DATE AS OF CHANGE**: 20260428

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Custom Truck One Source, Inc.
- **CENTRAL INDEX KEY:** 0001709682
- **STANDARD INDUSTRIAL CLASSIFICATION:** SERVICES-EQUIPMENT RENTAL & LEASING, NEC [7359]
- **ORGANIZATION NAME:** 07 Trade & Services
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** DEFA14A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-38186
- **FILM NUMBER:** 26909867

**BUSINESS ADDRESS:**
- **STREET 1:** 7701 INDEPENDENCE AVENUE
- **CITY:** KANSAS CITY
- **STATE:** MO
- **ZIP:** 64125
- **BUSINESS PHONE:** (816) 241-4888

**MAIL ADDRESS:**
- **STREET 1:** 7701 INDEPENDENCE AVENUE
- **CITY:** KANSAS CITY
- **STATE:** MO
- **ZIP:** 64125

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** NESCO HOLDINGS, INC.
- **DATE OF NAME CHANGE:** 20190730

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Capitol Investment Corp. IV
- **DATE OF NAME CHANGE:** 20170619

**UNITED STATES**

**SECURITIES AND EXCHANGE COMMISSION**

 **Washington, D.C. 20549**

 **SCHEDULE 14A**

 **PROXY STATEMENT PURSUANT TO SECTION 14(A) OF**

 **THE SECURITIES EXCHANGE ACT OF 1934 (Amendment No.)**

Filed by the Registrant ⌧&nbsp;&nbsp;&nbsp;&nbsp;

Filed by a Party other than the Registrant □

Check the appropriate box:

□ Preliminary Proxy Statement

□ **Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))**

□ Definitive Proxy Statement

⌧ Definitive Additional Materials

□ Soliciting Material Pursuant to §240.14a-12

**Custom Truck One Source, Inc.**

(Name of Registrant as Specified in its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

⌧ No fee required.

□ Fee paid previously with preliminary materials.

□ Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11.

![](ctoscard2026001.jpg)

Your Vote Counts! \*Please check the meeting materials for any special requirements for meeting attendance. Smartphone users Point your camera here and vote without entering a control number For complete information and to vote, visit www.ProxyVote.com Control # V92758-P48491 CUSTOM TRUCK ONE SOURCE, INC. 7701 INDEPENDENCE AVE. KANSAS CITY, MO 64125 CUSTOM TRUCK ONE SOURCE, INC. 2026 Annual Meeting Vote by June 10, 2026 11:59 PM EDT You invested in CUSTOM TRUCK ONE SOURCE, INC. and it's time to vote! You have the right to vote on proposals being presented at the Annual Meeting. This is an important notice regarding the availability of proxy materials for the stockholder meeting to be held on June 11, 2026. Vote Virtually at the Meeting\* June 11, 2026 9:00 AM EDT Virtually at: www.virtualshareholdermeeting.com/CTOS2026 Get informed before you vote View the Notice and Proxy Statement and Annual Report online OR you can receive a free paper or email copy of the material(s) by requesting prior to May 28, 2026. If you would like to request a copy of the material(s) for this and/or future stockholder meetings, you may (1) visit www.ProxyVote.com, (2) call 1-800-579-1639 or (3) send an email to sendmaterial@proxyvote.com. If sending an email, please include your control number (indicated below) in the subject line. Unless requested, you will not otherwise receive a paper or email copy.

------

![](ctoscard2026002.jpg)

Vote at www.ProxyVote.com Prefer to receive an email instead? While voting on www.ProxyVote.com, be sure to click "Delivery Settings". Voting Items Board Recommends V92759-P48491 THIS IS NOT A VOTABLE BALLOT This is an overview of the proposals being presented at the 2026 Annual Meeting. Please follow the instructions on the reverse side to vote on these important matters. 1. To elect each of the three Class A directors to serve until the 2029 annual meeting of stockholders and until his or her successor is duly elected and qualified. For Nominees: 01) Paul Bader 02) Mark D. Ein 03) David Glatt 2. To ratify the appointment of Ernst & Young LLP as the company's independent registered public accounting firm for its fiscal year ending December 31, 2026. For NOTE: To transact such other business as may properly come before the Annual Meeting or any adjournments or postponements thereof.

------