The overall goal of political advertising reform and regulation in the UK should be to foster a transparent, trustworthy, diverse, and competitive political advertising market.
Digital political advertising carries well-documented risks — opaque funding, misuse of personal data, and the amplification of mis- and disinformation. It also offers clear benefits: campaigns can reach voters directly, efficiently, and at scale, which is especially valuable in an algorithmically mediated information environment that often favours extreme content. Over more than a decade of study, our research has found that the benefits of digital political advertising generally outweigh the costs, but this gap could be (positively) widened with specific policy interventions.
Government should use legislation to create an online political advertising market with the following features:
1/ Transparency: All political advertisers should register and verify their UK identity and disclose their funding sources. Near-real-time reporting should provide details on ad content, targeting parameters, spend, and impressions. Archiving ad content ensures accountability over time. Transparent, accessible data allows regulators, media, and civil society to scrutinise campaigns effectively, prevent “shadow” spending, and enforce rules consistently. Transparency rules should be “always on”.
2/ Trustworthiness: Verification of advertisers ensures that most digital advertising comes from UK-based actors with a verifiable track record in politics, standing or likely to stand candidates, and with known financial backers. Polling-day advertising restrictions align with broadcast rules, preventing last-minute misuse and supporting electoral integrity. Trustworthiness measures, reinforced by transparency, build voter confidence that campaigns are legitimate, auditable, and compliant with spending limits.
3/ Competition: Common standards for transparency and trustworthiness make it easier for new services to offer political advertising to parties and candidates. Regulation should actively support opportunities for political advertisers beyond the two (current) largest digital platforms (Meta and Google).
4/ Plurality: Voters should encounter multiple candidates and viewpoints. Digital advertising spending caps ensure campaigns are treated fairly and no single campaign locally or nationally is able to dominate the information space.
This last point is crucial. At the 2024 election, party and candidate spending limits were significantly raised. These new ceilings allowed digital advertising spending to reach record levels and enabled the largest parties to vastly outspend smaller opponents on digital. Without intervention, there is a clear risk of an escalating arms race in digital political advertising.
We propose a framework of pragmatic, proportionate, and future-proof spending caps:
For party campaigners:
“No more than one third of regulated campaign spending, or £1 million, whichever is higher, may be spent on paid digital political advertising, subject to an absolute maximum of 50%.”
For candidates:
“A candidate’s campaign may spend up to £5,000 on digital advertising, or one third of their spending limit, whichever is higher.”
For by-elections:
“Digital advertising spending by candidates is capped at £20,000.”
For national parties targeting individual seats:
“A party campaigner can spend no more than the candidate limit on ads targeting a specific seat (or equivalent multiples of that limit if the ads target more than one seat).”
For non-party (third party) campaigners:
“A registered non-party campaigner may spend no more than £10,000 or 50% (whichever is higher) of their total regulated campaign spending on digital advertising.”
And:
“A registered non-party campaigner may spend no more than £2,000 on digital ads targeting a specific seat (or equivalent multiples of that limit if the ads target more than one seat).”
And:
“Non-party campaigners below the £20,000 registration threshold (£10,000 in Scotland, Wales or Northern Ireland), can spend no more than £10,000 on digital advertising and no more than £1,000 on digital ads targeting a specific seat (or equivalent multiples of that limit if the ads target more than one seat).”
Taken together, these measures:
- Prevent unlimited and escalating digital advertising spend
- Protect smaller and digital-first campaigns by giving them a proportionally higher allowance
- Preserve the balance between national and constituency-level campaigning, which is central to the UK’s electoral system
- Ensure the primacy of candidates and parties in UK campaigns with comparable and fair limits on non-party campaigners
- Increase confidence in a system the public distrusts
Conclusion
By adopting proportionate spending caps alongside transparency and trustworthiness requirements, the UK can maintain the benefits of digital political advertising while ensuring a level playing field, promoting fair competition, and safeguarding voter trust.
The framework we propose is simple to enforce, scalable, and adaptable to future technological and campaign innovations, providing a strong, practical foundation for a transparent, trustworthy, and pluralistic political advertising ecosystem.