The Duke of Sussex wrote to Home Secretary Shabana Mahmood shortly after her appointment and submitted a formal request for a risk assessment to the Executive Committee for the Protection of Royalty and Public Figures (Ravec), which is overseen by the Home Office, a source close to the duke said in October.
The Home Office has now ordered a threat assessment for the first time since 2020, the Sun reported.
It comes after Prince Harry lost an appeal in May challenging the dismissal of his High Court claim against the Home Office over the decision of Ravec that he should receive a different degree of taxpayer-funded protection when in the UK.
The legal challenge came after Harry and the Duchess of Sussex left the UK and first moved to Canada, and then California, after announcing they wanted to step back as senior royals.
Harry said the Court of Appeal decision meant it is now "impossible" for him to bring Meghan and their children, Prince Archie and Princess Lilibet, back to the UK safely.
Ravec has instructed its Risk Management Board to reassess his threat level, the Sun reported.
The newspaper said the process is already under way and a decision is expected in January.
A government spokesperson said: "The UK government's protective security system is rigorous and proportionate.
"It is our long-standing policy not to provide detailed information on those arrangements, as doing so could compromise their integrity and affect individuals' security."
During Harry's last visit to the UK in September, a "known stalker" came "within feet" of him on two occasions, according to a report in The Telegraph.
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