"These changes are designed to help users better understand the unaffiliated nature of PCF accounts and reduce the risk of confusion or impersonation," the company said in a post on Saturday.
It encouraged affected accounts to update their profiles by the enforcement date.
The changes will also apply for fan and commentary accounts, it said.
"Hopefully this includes all the thousands of fake variations of Elon Musk accounts," wrote one user in response to X's post about its policy update.
"About time, I get a fake Elon account contacting me almost once a week," wrote another.
There are a number of parody accounts for the platform's owner, identifying themselves as impersonations in various ways.
Posts viewed by the BBC from Elon Musk parody accounts ranged from memes and jokes, to promoting cryptocurrency and car giveaways.
A recent post by one Elon Musk parody account, which has more than one million followers, told users to "like and comment" for the chance to win a Tesla.
The post has received 428,000 likes and more than 200,000 replies.
X rolled out labels for parody accounts in January - building on its rules requiring users engaging in impersonation for the purpose of entertainment to identify themselves as such.
These, and the platform's blue tick verification system, have been cited as tools to prevent misleading impersonation while allowing speech and discussion.
But the effectiveness of such measures have been disputed.
The EU said in July 2024 that the blue ticks breached its online content rules, with its "verified" blue tick accounts having the potential to "deceive" users.
Musk called the EU's rules "misinformation", in response.
Following his takeover in November 2022, the Tesla chief executive said accounts engaging in unlabelled impersonation would be banned.
Many parody accounts on X identify their parody nature in brackets at the end of user names, but this is not a fool-proof measure.
If a parody account's name is particularly long, and only a shortened version appears in feeds or replies, users can unwittingly duped - especially if the account's image matches that of the real person.
