NOTE: This is not legal advice.
This article is focused on United States definitions and usage; other countries may differ. You can help by editing this wiki!
For those who live in conventional homes and apartments, these three are usually all the same, though some people have their mail delivered to a PO Box or elsewhere.
For nomads, things are more complex. Society is set up for conventional living situations, so a little extra work is required for those who wish to live on the road.
Approaching these choices methodically will keep mistakes and distress to a minimum. If your sticks-and-bricks address was acceptable from a domicile/residence point of view it is probably best to keep them. You already have official ID, etc. Mail forwarding can be anywhere.
See also: suggested timeline for hitting the road
Your residence (aka physical address) is the place you would call home if you lived there full time. It is important that all your contacts know that you do not receive mail at this address, unless the person who lives there is your de facto mail forwarder; you receive mail at your mailing address instead.
For those who live in conventional homes and apartments, the state where their home is located is automatically their domicile. Nomads may not be at home or have a home but must still have a legal residence.
The Patriot Act requires all financial institutions (banks, investment companies, etc.) to collect identifying information on their customers. This is known as Know Your Customer, or KYC. Many of these institutions have interpreted KYC to disallow mail forwarders and mailbox services as legal residences.
There is a houseless way to help the institution satisfy KYC. The guidance is given in FINRA regulations:
for an individual, a residential or business street address, or for an individual who does not have a residential or business street address, an Army Post Office or Fleet Post Office box number, or the residential or business street address of a next of kin or another contact individual… – FINRA2)
Your domicile is the state where the legal residence is3). Your domicile will be:
Domicile is a combination of two factors namely, residence and intent to remain… An individual may have several residences whereas; s/he will have only one domicile. Domicile is more used in reference to personal rights, duties and obligations[ii].4)
State income taxes range from 0% to 7% or more. If you have high earnings, this variation could make a significant difference in your tax expenses.
Wikipedia: Income tax by state
State sales taxes vary from 0% to 8% or more. If you spend a lot, or purchase a vehicle in these states, this variation could make a significant difference in your tax expenses.
Tax-Rates.org: Sales Tax by State
Wikipedia: Vehicle inspection in the U.S.
Wikipedia: Concealed carry in the U.S. USACarry.com: CC permit reciprocity
Your mailing address is the place your mail should be sent. This is usually a mail forwarding service for most nomads, but may also be the home of a trusted relative or friend who preferably does not expect to move for a long time.
A mail forwarding service provides a mailing address (usually in your domicile state) and collects your mail. You let the forwarder know where you are (or will be) and they bundle your mail and send it to you. Some services will scan mail for viewing on the web, watch for critical pieces of mail to come in, etc.
If you intend to use your mail forwarding service address as your domicile address take note of the county where the forwarded is located. There are reports that many mail forwarding service addresses have been blacklisted and may not suffice as a residence or physical address.
There are also ad hoc ways to receive packages.
The United States Postal Service runs a forwarding service called Premium Forwarding Service (PFS).18) It is limited in usefulness, as it is very expensive and can be active for only a year.
The USPS may provide P.O. Boxes to homeless persons under certain circumstances, or they can use General Delivery to send things to some Post Offices.
Mail centers associated with iPostal1 or similar offer digital mailboxes. Mail can be scanned, emailed, viewed online, physically forwarded, etc. {Secessus uses a local mail center that has the iPostal1 backend and it works well enough. About $99/yr plus the cost of any extra scans, forwards, etc}