Nazanin Zaghari-Ratcliffe, who works for the Thomson Reuters Foundation (TRF) -- the media organisation's philanthropic arm -- was told about the court date by the country's deputy prosecutor yesterday, Richard Ratcliffe said.
The new charge could result in a further lengthy sentence.
The case has become highly politicised in Britain after Foreign Secretary Boris Johnson was accused of jeopardising Zaghari-Ratcliffe's defence.
He told a parliamentary committee earlier this month that she had been training journalists in Iran before she was arrested -- a comment her employer and her family said was wrong.
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The requests were under review, the foreign office said afterwards.
Zaghari-Ratcliffe was arrested at Tehran airport on April 3, 2016 after visiting relatives in the country with her young daughter.
Iran's elite Revolutionary Guards accused her of having taken part in the "sedition movement" of protests that followed the disputed 2009 re-election of then hardline president Mahmoud Ahmadinejad.
She was sentenced to five years in jail, before authorities last month presented extra charges.
Ratcliffe will attend a march on Saturday in the family's home neighbourhood of West Hampstead in London, alongside local resident and Oscar-winning actress Emma Thompson, who will lead calls for Zaghari-Ratcliffe's release.
Meanwhile, an online petition for her release has collected more than 1.3 million signatures.
Ratcliffe also revealed Thursday that his wife has not developed breast cancer as recently feared.
However, the lumps responded to prescribed medication, indicating they are not cancerous, he told British media.
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