> ## Documentation Index
> Fetch the complete documentation index at: https://docs.alvys.com/llms.txt
> Use this file to discover all available pages before exploring further.
# How to add a USDOT# to a Subsidiary
> Add or update the USDOT number on a subsidiary in the Company Profile, use FMCSA pre-fill, and resolve a USDOT# that is already in use.
Adding a USDOT# (also called a DOT number, DOT#, US DOT number, USDOT number, or Department of Transportation number) to a subsidiary lets Alvys identify your operating entity for regulatory purposes and, when creating a new subsidiary, automatically fills in company details from the FMCSA.
## Overview
The USDOT# is a unique identifier assigned by the Federal Motor Carrier Safety Administration to entities involved in interstate and intrastate commerce. In Alvys, you can attach a USDOT# to a subsidiary either at the time you create the subsidiary or after the subsidiary already exists.
When you enter a USDOT# during subsidiary creation, Alvys looks up that number with the FMCSA and pre-fills the subsidiary's name, MC#, company type, physical address, contact email, and phone number. You can review and update any of those pre-filled values before saving.
### Ownership verification
Creating a subsidiary now includes a step that confirms you own the MC# or USDOT# you are registering, before the subsidiary is created. Once you pass it, the verified carrier details pre-fill the form.
Three things follow from this:
* **The verified number is locked.** After a subsidiary is verified, its MC# and USDOT# can no longer be edited. The number prints on rate confirmations and invoices, so a correction is a support request rather than a self-serve edit.
* **An MC# or USDOT# already registered by any Alvys account is refused,** and the reason is shown. This is wider than your own account: another company already operating under that authority blocks it too.
* **If verification cannot be completed, the subsidiary is not created.** Alvys refuses rather than letting an unverified authority through. Try again shortly.
Ownership verification is rolling out to accounts gradually, so you may not see this step yet.
## Prerequisites
You must have the **Admin**, **Partner Admin**, or **Support** role to create a subsidiary or edit the company profile. Other roles can open the company profile and read it, but the owner phone, owner email, and operating countries are shown read-only, and **New Subsidiary** is not offered. A field with nothing in it reads **Not Set** rather than inviting you to add a value you would not be allowed to save.
If you are a Biller, Accountant, Dispatcher, or Operation Manager and the option to create a subsidiary is missing, that is expected. It is a role restriction, not a fault and not a plan limit.
If you are adding a USDOT# to a new subsidiary, have the USDOT# available before you begin. If you are adding a USDOT# to an existing subsidiary, that subsidiary must not already have a USDOT# assigned; each subsidiary can only have one USDOT#.
## Steps
1. **Open Company Profile:**
* Select Management in the left navigation.
* Select Company Profile.
* Locate the subsidiary you want to update in the subsidiary list on the left side, or proceed to create a new subsidiary.
2. **Add the USDOT# to a new subsidiary (**If you are creating a new subsidiary**)**:
* Select the option to create a new subsidiary.
* Enter the USDOT# in the USDOT# field.
* Alvys contacts the FMCSA and pre-fills the subsidiary name, MC#, company type, physical address, contact email, and phone number based on the USDOT# you entered.
* Review the pre-filled values. You can edit any of them before saving.
* Complete all required fields (physical address and remit address are required) and save the subsidiary.
*Create Subsidiary form with the USDOT# field highlighted and FMCSA pre-fill visible.*
\*\*Add the USDOT# to an existing subsidiary (\*\*If the subsidiary already exists and does not yet have a USDOT#):
*Subsidiary details page showing the USDOT# field with the link to add a DOT number.*
## Variations
Not all subsidiaries have an MC#. For intrastate-only carriers, the USDOT# alone is sufficient. The FMCSA pre-fill works as long as the USDOT# is valid and registered in the FMCSA database.
## Troubleshooting
### USDOT# field does not appear or cannot be edited
* The USDOT# and MC# fields are locked after a subsidiary is created. You cannot edit a USDOT# that was entered at creation time. If the USDOT# on file is incorrect and you need it changed, contact Alvys support; this is not something that can be self-served, because these fields are locked by design to prevent duplicate subsidiaries in the system.
### FMCSA pre-fill does not populate any fields
* The pre-fill depends on the FMCSA returning a match for the USDOT# you entered. If no data appears, verify that the number is correct and is registered with the FMCSA. The pre-fill is informational only; you can still enter all required fields manually.
### Cannot create a subsidiary with a USDOT# already in use
* The system prevents creating a new subsidiary if the MC# or USDOT# is already registered, and shows you the reason. The check covers every Alvys account, not only your own, so a number held by another company is refused as well. Use a unique USDOT# for each subsidiary, and contact Alvys support if a number you own is reported as already in use.
## FAQs
**Q: Can I edit the USDOT# after a subsidiary has been created?**
**A:** No. Once a subsidiary is created, the USDOT# and MC# fields are locked and cannot be edited. If a correction is needed, contact Alvys support.
**Q: Is a USDOT# required to create a subsidiary?**
**A:** No. The USDOT# is optional when creating a subsidiary. You can create a subsidiary without one and add the USDOT# afterward using the link in the subsidiary details.
**Q: Does adding a USDOT# to an existing subsidiary update any other fields automatically?**
**A:** No. The FMCSA pre-fill only applies during new subsidiary creation. Adding a USDOT# to an existing subsidiary attaches the number only; it does not update the subsidiary name, address, or other fields.
**Q: Can two subsidiaries share the same USDOT#?**
**A:** No. The system prevents creating a subsidiary with a USDOT# that is already registered, whether the existing subsidiary is in your account or in another company's.