Prime Minister John Key says he is comfortable with MPs owning their own electorate offices and then claiming a Parliamentary subsidy.
It's been revealed six National MPs and one Labour Party MP have a financial interest in their office buildings, and lease them to Parliamentary Services.
Mr Key owns his electorate office and says he has no objection to the practice, providing MPs are acting within the rules.
He would not discuss specific details of his own case, but says he has been subsiding the taxpayer by charging below market rental, based on a 2003 valuation.
Mr Key says there are enough checks and balances within the current system.