Facebook will begin requiring political advertisers in the UK to confirm their identity and location, and disclose who paid for the ad.
Ads on Facebook and Instagram will be accompanied with a 'paid for by' disclaimer following calls for regulation. Political ads will be housed in an ad library for seven years.
Rob Leathern, director of product management at Facebook, said in a company statement that the UK decision should help "shine a brighter light on political advertising and offers a resource for news organisations, regulators, watchdog groups and the public to hold advertisers more accountable."
The UK transparency measures were meant to roll out on 7 November, but Facebook pushed back the verification protocol following a series of examples showing how the system was open to abuse.
In the US, Facebook will exempt promoted content from news outlets that mention political issues from its ad archive.
Publishers had been critical of the practice, which was introduced last spring. The initial authorization initiative was created to prevent foreign interference in elections, spurred by the fake news epidemic during the 2016 presidential election.
Leathern said Facebook wants to support journalism, and admitted the news indexing process was problematic. Facebook will work to ensure ads from news outlets no longer get archived.
"We'll also continue working with publishers, platforms and fact-checkers to increase safeguards and transparency in this area, which should lead to greater accountability for both Facebook and our advertisers," he said.
Until its news index is fully rolled out, Facebook will use lists from a variety of established news industry groups to help inform which UK news outlets should receive authorization exemptions.
Next year, Facebook plans to begin determining which publishers should be exempt from all country-wide ad libraries.
Earlier this week, global MPs questioned Facebook on its advertising model and admonished the site for its poor record on transparency.