Angela Rayner, the deputy prime minister, has admitted to underpaying stamp duty on an £800,000 flat she bought in May this year.

According to Rayner, who is also housing secretary, she incorrectly paid the lower stamp duty rate on the property in Hove, East Sussex, with some estimating that the bill could be as much as an extra £40,000. She says she will now pay the correct amount.

After receiving criticism from opposition MPs in the House of Common’s during today’s PMQs, prime minister Keir Starmer said he stood by his deputy.

In a statement, Rayner said: “When purchasing the property my understanding, on advice from lawyers, was that my circumstances meant I was liable for the standard rate of stamp duty.

“However, given the recent allegations in the press I have subsequently sought further advice from a leading tax counsel to review that position and to ensure I am fully compliant with all tax provisions.

“I have now been advised that although I did not own any other property at the time of the purchase, the application of complex deeming provisions which relate to my son’s trust gives rise to additional stamp duty liabilities.

“I acknowledge that due to my reliance on advice from lawyers which did not properly take account of these provisions, I did not pay the appropriate stamp duty at the time of the purchase. I am working with expert lawyers and with HMRC to resolve the matter and pay what is due.

“The arrangements I have set out reflect the reality that family life is rarely straightforward, particularly when dealing with disability, divorce and the complexities of ensuring your children’s long-term security. Every decision I have made has been guided by what I believe to be in my children’s best interests.

“I deeply regret the error that has been made. I am committed to resolving this matter fully and providing the transparency that public service demands. It is for that reason I have today referred myself to the independent adviser on ministerial standards, and will provide him with my fullest cooperation and access to all the information he requires.”