London assembly officials are weighing up whether to launch an investigation into Zack Polanski after he admitted he may have failed to pay the correct council tax while living on a houseboat in the capital.

The Green party leader has faced questions over whether the houseboat, moored in east London, was his primary residence. A spokesperson for his party had described the situation as an “unintentional mistake” and said Polanski had “immediately taken steps” to pay any tax owed.

Last week, Anna Turley, the chair of the Labour party, wrote to the Greater London authority (GLA) monitoring officer to call for an investigation into Polanski, as an elected member of that body, over whether he had breached the standards to which he was bound.

The monitoring officer is understood to be considering whether to launch an investigation into the issue. In email correspondence reported by the Times, they said: “I am treating your correspondence as a formal complaint under the GLA’s standards regime.

“The monitoring officer is required to consider complaints about the conduct of elected members in accordance with the approved GLA member code of conduct complaints procedure.

“This will now be considered in accordance with the authority’s established procedures, including an initial assessment of whether an investigation is required.”

When a formal complaint is made, the subject of the complaint has seven to 10 days to respond in writing. After two independent people outside the GLA, which comprises the mayor of London and the 25 London assembly members, are consulted and provide advice, the monitoring officer will make a decision.

Assembly members can face sanctions if found to be in breach of ethics rules, though these are often minor and can result in a meeting or apology.

The Green party had told the Times that Polanski rented a room at another address where council tax was included in the rent and stayed on the boat only “occasionally”. Government guidance says a person may be liable for council tax on a boat if it is their “sole or main” residence. The Times also reported the existence of an advertisement for the sale of the boat in which Polanski’s partner wrote: “We are moving to a house and so will sadly be leaving the gorgeous community behind.”

Waltham Forest council has confirmed it launched an investigation into whether any council tax was owed on the mooring where the houseboat was situated.

When writing to the monitoring officer last week, Turley cited section 106 of the Local Government Finance Act 1992, which requires public office holders, including GLA members, who are two months or more in arrears on their council tax to declare that fact at meetings considering certain financial matters. It also prohibits them from voting on such matters.

A Green party spokesperson said: “Zack is aware of complaints made by the Labour party and the Conservative party. He denies any wrongdoing and will cooperate fully with the official process to answer any queries.”

A GLA spokesperson said: “The monitoring officer has received two complaints that AM Zack Polanski breached the Greater London authority’s members’ code of conduct.

“Those complaints are being considered under the GLA’s usual process. It would not be appropriate to comment further while this process is ongoing.”