Christopher Harborne, the Thailand-based crypto investor who has given millions of pounds to Reform UK, would be unlikely to get around a planned cap on overseas political donations even if he has registered to vote in the UK, it is understood.

Harborne, who also gave Nigel Farage, the Reform leader, £5m as a “gift”, has registered to vote in Hampshire, the Times reported, with a spokesperson for the billionaire quoted in the paper saying that he had decided to become a “registered voter in the UK”.

The move could be viewed as an attempt to help Harborne get around planned changes to the political donations system, which could put a £100,000 annual cap on Britons based abroad, as well as other measures such as blocking donations made in cryptocurrency.

The Times reported Harborne’s decision to register to vote as a possible way for him to continue giving large sums to Reform, citing an interview in April in which he said the government should not be able to stop him donating as he chose, adding: “Where there’s a will, there’s a way.”

However, the planned changes to donations, among 15 recommendations in an independent report in March by Sir Philip Rycroft, a former senior civil servant, set out the idea that a cap of between £100,000 and £300,000 a year should apply to “British voters living abroad”.

While the definition of this is yet to be decided by ministers, Rycroft’s report set out that the basis is expected to be whether or not someone is based in the UK, not just if they are registered to vote. Decisions on individuals would be left to election officials at local councils, who decide whether a voter is “normally resident” in the UK for the purposes of their address on the electoral register.

Harborne, who has donated £15m to Reform in the past 12 months, as well as gifting Farage £5m shortly before the 2024 elections, has been based in Thailand for more than five years, where he uses a Thai name, Chakrit Sakunkrit.

If he wanted to get around the overseas donations cap, he may have to return to live in the UK, which would make him liable for UK tax on earnings from a fortune estimated to be more than £18bn.

In his report, Rycroft specifically linked the idea of taxation to the fairness or otherwise of political donations, writing: “Though many individuals’ decisions to move abroad are not financially motivated, it remains the case that wealthy individuals who have chosen to live abroad in order to have their wealth taxed abroad are nevertheless currently entitled to make unlimited donations to UK political parties.

“Despite choosing to minimise their contribution to the UK exchequer, these individuals have the opportunity to make potentially gamechanging donations into British politics.”

After the review was published, Steve Reed, the communities secretary, said the legislation would be applied retrospectively from March subject to parliamentary approval, as the move was urgently needed to protect UK democracy.

Harborne’s donations hit public prominence after the Guardian revealed in April that Farage received£5m shortly before announcing he would stand in the 2024 British general election.

Farage said the money was a gift, and thus did not need to be registered under rules requiring MPs to declare any potential interests in the 12 months before their election. He is facing a formal investigation by the parliamentary standards watchdog.

The Reform leader initially said the money was intended for personal security costs, and then that it was a reward for Brexit. After avoiding questions on the subject for some weeks, last week he grumpily rebuffed an interviewer’s questions on what he had spent the money on, saying it was “not any of your business”.

He said: “It’s an unconditional gift. I can spend it on Ferraris if I want. That’d be entirely up to me,” he said, adding: “I can do what I want with it. I can put it on the horses.”

Harborne’s representatives were contacted for comment.