Image source, PA MediaGreater Manchester Police is reassessing its decision not to investigate claims Labour's deputy leader Angela Rayner gave false information on official documents.
It followed a complaint from a Conservative MP.
Ms Rayner has denied any wrongdoing relating to where she was registered as living after her marriage in 2010.
Tory MP James Daly had asked police to investigate whether she had given false information or broken electoral rules.
Earlier this month, the police said they had found no evidence any offence had been committed.
However, in a statement a spokesperson for Greater Manchester Police said: "We have received a complaint regarding our decision not to investigate an allegation and are in the process of reassessing this decision.
"The complainant will be updated with the outcome of the reassessment in due course."
It followed claims made in a book by Lord Ashcroft, a former Conservative Party deputy chairman, about Ms Rayner's ex-council house on Vicarage Road in Stockport, Greater Manchester.
Questions were then raised about whether the house was her principal residence at the time, a distinction which could have had an impact on how much tax she owed when it was sold.
Ms Rayner, nee Bowen, bought the semi-detached home in 2007, getting a 25% discount under the Right to Buy scheme introduced by former Conservative Prime Minister Margaret Thatcher.
In September 2010 she married Mark Rayner, who owned a separate house nearby in Lowndes Lane.
The Mail on Sunday, which is serialising the book, has reported Ms Rayner was registered as living at Vicarage Road on the electoral roll until she sold the property in 2015.
But she appears to have given two different addresses when she re-registered the births of two of her children in 2010 following her marriage to Mr Rayner.
In March 2015, two months before she became an MP, Ms Rayner sold the Vicarage Road property for £127,500, a gain of £48,500. The couple separated in 2020.
James Daly is the MP for Bury North, while Angela Rayner represents Ashton-Under-Lyne, another Greater Manchester constituency.
Ms Rayner has previously told the BBC she is the victim of a "smear" and has received professional advice that she owes no tax on the sale of her home.
"I've been very clear there's no rules broken. They [the Conservatives] tried to manufacture a police investigation," she said.