UK citizenship rules state that after five years Meghan could get indefinite leave to remain in the UK — allowing her to start her full citizenship bid.
However, she must not have left the UK for more than 270 days in the three years before applying for it.
This can be spread over the three years — but must include 90 days in the last year.
While experts say the UK Home Office can show discretion over an absence, Meghan would have to put forward a convincing argument to continue her claim.
Michael Marziano, senior immigration lawyer at Westkin Associates, told the publication: “The US citizen has to be living in the UK with the British partner when the application to extend the partner visa is made.
“They must intend to continue to live together permanently in the UK.
“If there has been any period throughout the first 2½ years where they have not lived together in the UK, government guidance states there must be good reason for this.
"It must be consistent with their continued intention to live in the UK permanently.”
Harry and Meghan are currently both residing in Canada, with their son Archie.