The Auditor-General's office says it needs more information before deciding whether Finance Minister Bill English is entitled to an out-of-town allowance.
In a letter to the leader of the Progressive Party, Jim Anderton, the office says it is making preliminary enquiries about MPs' and ministers' accommodation entitlements before deciding whether a full inquiry is warranted.
Mr Anderton has requested that the office clarify a speaker's ruling that Dipton, in Southland, is Mr English's primary residence.
Mr English has been criticised following revelations he received more than $900 a week for ministerial accommodation and related expenses for a Wellington home owned by a family trust. He has since paid back $14,000.
Mr Anderton says an Auditor-General's ruling in 2001 suggests if an MP's spouse and children live in Wellington, as is the case with Mr English, the capital is the primary place of residence.
He says the rules, in his view, are clear and must be adhered to and the matter is not a vendetta against Mr English.