A domain is registered in a developer's account, or an agency's, and you want it in yours. The reflex is a transfer to another registrar, which is slower, costs money, and is usually not what the situation needs.
Two different operations
An internal push moves a domain between two accounts at the same registrar. Minutes, free, no year added to the registration, no lock afterwards.
A registrar transfer moves the domain to a different company. Days, requires an authorisation code and an unlocked domain, usually adds a year and a charge, and locks the domain against further transfers for sixty days.
If the current registrar is one you are happy with, the push is obviously better. Most people do not know to ask for it.
How a push works
The exact wording differs ("push", "account change", "move to another account") but the shape is the same.
The current holder initiates it, giving the receiving account's username or the email address on it. The receiving account gets a notification and accepts. Done.
The receiving account must usually already exist at that registrar, so create it and send the exact identifier the registrar asks for. A push sent to a mistyped username fails silently and is a surprisingly common source of delay.
Nameservers do not change
This is the practical advantage. A push moves the domain between accounts without touching its DNS settings, so the website and email keep working throughout with no interruption at all.
A registrar transfer can reset nameservers to the new registrar's defaults, which takes a site offline until someone notices. That difference alone justifies preferring a push when it is available.
When the other party will not cooperate
Sometimes the account holder is unreachable, or unwilling.
What matters then is the registrant contact on the domain. The legal owner as recorded in the registration, which is not necessarily the account holder. If your name or your company is the registrant, the registrar has a process for recovering control, and it is worth contacting them directly rather than negotiating.
If the registrant is someone else, that is a genuinely different problem, and it is why checking who the registrant is should not wait until there is a dispute.
Verify afterwards
A push moves the account. It does not always update the registrant contact.
After it completes, check the registration details and correct them if they still name the previous holder. A domain in your account with someone else recorded as the owner is only half moved, and the half that is missing is the one that matters if there is ever a disagreement.
What to check after transferring a domain goes over the full list, and it applies to a push as well.
When a transfer is the right choice
When you want to leave the registrar, consolidating everything in one place, or because the current one is expensive or hard to work with.
Then the ordinary process applies: unlock the domain, get the authorisation code, start the transfer at the new registrar, approve it. Getting your EPP authorisation code goes into it.
One thing to do first: record the current DNS records before transferring. If nameservers reset, you will need to recreate them, and reconstructing a zone from memory while the site is down is avoidable work.
The sixty-day rules
Two exist and they are separate.
A domain transferred between registrars cannot be transferred again for sixty days. A domain that has had its registrant contact changed may also be locked for sixty days, depending on the registrar's settings.
The second catches people who update ownership details and then try to transfer immediately. If a move is planned, do the transfer first and correct the contact details afterwards.
Domain locking goes over the ordinary lock, which is a protection worth keeping on the rest of the time.
What the receiving account must have ready
A push fails silently more often than it fails loudly, and nearly always for one of three reasons on the receiving side.
The account must already exist at that registrar. Creating it after the push is initiated does not help; the push simply cannot find a destination.
The identifier must be exactly what the registrar asks for. Some want a username, some the account email, some a customer number. Sending the wrong one produces a failure that names nothing useful.
The receiving account must be verified and in good standing. An account created minutes earlier with an unconfirmed email address is frequently ineligible to receive.
Confirm all three with the other party before initiating, rather than discovering them through a failed attempt that has to be redone.
Check what actually moved
A push transfers the registration. It does not necessarily transfer everything associated with it.
whois example.com | grep -iE 'registrar|registrant|name server|status|expir'
Four things to verify afterwards, because any of them can be left behind: the registrant contact, which frequently still names the previous holder; auto-renewal, which is an account setting in place of a domain property; privacy protection, which may lapse; and DNS records, if the previous account was also hosting the zone.
That last one is the damaging case. A domain pushed away from an account whose nameservers were hosting the zone keeps pointing at nameservers the new account does not control, and they may stop answering later. Secondary DNS and what happens when DNS fails explains what that outage looks like.
Moving many domains at once
Most registrars support pushing several domains in one operation, and it is worth using rather than repeating the process.
Take an inventory first, name, expiry, nameservers and registrant for each, and check it again afterwards. On a batch, a domain that failed to move is easy to miss, and the discovery usually comes at its renewal.
Managing a portfolio of domains and renewals explains the inventory, which is the same document either way.
When a domain is held hostage
A developer or agency that will not release a domain is a commercial dispute, and the technical routes are limited.
What matters is the registrant of record. If that is you or your company, the registrar has a process for restoring control to the registered owner, and contacting them directly is more effective than continuing to negotiate.
If the registrant is the other party, the domain is legally theirs regardless of who paid for it, and the resolution is commercial rather than technical.
Either way, gather evidence first: invoices, correspondence showing the arrangement, and any written agreement. That is what the registrar will ask for, and it is much easier to assemble before the relationship deteriorates further. Inheriting a website nobody documented explains checking this before it becomes urgent.