It is possible to use a registered agent’s address to apply for an EIN, but most lawyers advise against it.
A registered agent address is fine for receiving correspondence from the Secretary of State and for receive service of process.
But most lawyer advise that you should use your office address – or if you don’t have an office, your home address – to receive the EIN number after your application is processed.
See also: What is a registered agent
You Need a Mailing Address
The address you provide for your LLC on the EIN form (the SS-4 form in IRS parlance) is entirely private, so it really just needs to be address where you will certainly receive mail safely and effectively.
It just needs to be a US address.
Theoretically a registered agent’s address may work, as long as they offer full mail forwarding, but in this case it is recommended to use an alternative address.
It Should Be a Business Address
One reason for this is the IRS wants to know what is the actual address of the office of the firm to determine where it is doing business and hence its tax status.
If you provide the registered agent’s address, that’s the location where they are doing business rather than your LLC.