The Broadcasting Standards Authority says a National Party election advertisement with the tagline 'Let's tax this', parodying Labour's campaign motto 'Let's do this' does not breach the Election Programmes Code.
The BSA has not upheld a complaint that the ad was inaccurate and misleading.
The authority found that the advertisement "promoted National's views of Labour's various tax announcements and, in critiquing those announcements, contrasted National with the Labour Party, with the aim of promoting its own party".
As such, the advertisement promoted the political opinions of National regarding Labour's policies rather than making assertions of fact, the authority said.
The BSA said it considered whether the advertisement breached the standard under the Election Programmes Code, which requires factual information to be clearly distinguishable from opinion or advocacy.
It noted that the standard is aimed at ensuring that political parties and broadcasters take care not to mislead viewers by presenting political assertions as statements of fact.
The authority said it was satisfied that it would be clear to viewers that the election programme was a campaign advertisement for the National Party, which clearly advocated National's own views on Labour's tax policy in an effort to convince voters to vote for National.
"We consider it would have been clear to viewers that the advertisement did not contain factual information, but rather National's own analysis of Labour's comments, policies and tax announcements," it said.
In making its decision, the BSA said, it took into account the public interest in election programmes and party policies, and the robust political environment in the lead up to the general election.