The Reform UK leader spent around half an hour being questioned over the money last month, according to the Sunday Times. Farage maintains the gift was for his personal security and does not need to be declared.
The interview suggests the investigation may be nearing its conclusion, although Reform UK has not been informed that a report is finished. If the commissioner finds a serious breach of the rules, the matter passes to the standards committee, which can recommend sanctions including suspension from the Commons.
A suspension of more than 10 days, if approved by parliament, could trigger a recall petition and a second byelection in Farage's Clacton constituency.
The gift was first revealed by the Guardian in May. The rules require financial support related to an MP's role to be registered if given in the 12 months before they enter parliament. Farage has previously called the inquiry a personal matter.
Separately, Reform UK is planning a major reorganisation at its headquarters, including a shake-up of staffing. The party has already suspended James Orr, its head of policy, and Dan Jukes, Farage's close aide, pending an internal investigation into allegations they encouraged illegal foreign donations during an undercover sting by reporters from Verbatim.