The British-Iranian woman has been under house arrest in Tehran since being moved from jail last spring.
Her husband, Richard Ratcliffe, has written to the foreign office asking for details about the end of her sentence on 7 March, including what arrangements have been made for her to be given the correct papers to travel and how an ankle tag she wears will be removed, The Sunday Times reported.
Dominic Raab, the foreign secretary, said the government was “pushing as hard as we can” to free her after five years detention, saying negotiations between the two sides had “intensified” recently.
The incoming Biden administration in the US offered “additional possibilities” that Zaghari-Ratcliffe could be allowed to leave Iran, Mr Raab added.
The 42-year-old charity worker was at the airport returning to the UK after a holiday visiting her family in Iran when she was detained by the Iranian Revolutionary Guard.
She was transferred to an unknown location in Kerman Province, 1,000 kilometres south of Tehran, where she was held in solitary confinement before her release under house arrest due to the coronavirus pandemic in March.
The couple’s daughter, Gabriella, had her British passport confiscated and was sent to live with her grandparents in Iran.
Late last year Ms Zaghari-Ratcliffe was subjected to a fresh trial on charges of spreading propaganda against the regime and Iranian authorities have told her she will be returned to Evin prison following the hearings, which have been delayed.
Mr Ratcliffe has branded the charges “spurious”, saying they rely upon the same evidence used to convict her in 2016.
In an update on the campaign to free her last month, he said “lately the temperature raised” and the new court case “was opened, then adjourned, with the threat of more years”.
He said: “There has been a new crackdown of arrests and executions. We wait for normal life.”
Tehran has linked her imprisonment to a £400m debt Iran says it is owed by the UK over the sale of tanks in the 1970s.
Iran’s Tasnim News Agency reported this week that an amount equivalent to the UK debt had been added to the country’s 2020-2021 budget.
The money was linked to lawsuits brought by the Iranian Ministry of Defense in international courts, which the report said was presumed to include the UK bill.
Commenting on the hoped for March release, Kate Allen, Amnesty International UK’s Director, said: “After all Nazanin has been through – solitary confinement, denial of medical care, a grossly unfair trial and living with the threat of a further prison sentence – we’re not taking anything for granted.
“Nazanin shouldn’t have to wait a day longer for her release – but at the very least we hope 7 March sees Nazanin finally reunited with her family back here in Britain.”