14 CFR § 141.25

Each holder of a pilot school or a provisional pilot school certificate must maintain a principal business office with a mailing address in the name shown on its certificate.

The facilities and equipment at the principal business office must be adequate to maintain the files and records required to operate the business of the school.

The principal business office may not be shared with, or used by, another pilot school.

Before changing the location of the principal business office or the operations base, each certificate holder must notify the responsible Flight Standards office for the area of the new location, and the notice must be:

Submitted in writing at least 30 days before the change of location; and

Accompanied by any amendments needed for the certificate holder's approved training course outline.

A certificate holder may conduct training at an operations base other than the one specified in its certificate, if:

The Administrator has inspected and approved the base for use by the certificate holder; and

The course of training and any needed amendments have been approved for use at that base.