Today's Question Time will be shorter than usual after a process scuffle between Greens and National

"Today the Green Party offered, as per our long standing policy, our question to the Leader of the Opposition. They have chosen to not use this opportunity today," Greens Co-leader James Shaw said.

A departure from usual Question Time protocol means that only 11 primary questions will be asked in the House this afternoon, rather than the usual 12.

The Green Party, which usually allocates its questions to National, says its offer has been rejected today for the first time.

"Today the Green Party offered, as per our long-standing policy, our question to the Leader of the Opposition. They have chosen to not use this opportunity today," Greens co-leader James Shaw said.

The Greens are not technically in government and are "confidence and supply" partners to the Labour/NZ First Coalition Government.

This means they are able to ask questions in Question Time but in March last year, they instead opted to give their questions to National.

"Question time is to hold the Government of the day to account. The Green Party prefers to not ask patsy questions," Shaw said today.

"We are focused on supporting our Government's response on Christchurch – gun control laws, Royal Commission of inquiry and ensuring people directly affected get all the help they need."

But a National Party spokesperson said it wasn't a rejection of the Greens' question, it was a "House management issue".

Each Question Time, political parties are assigned a certain number of supplementary questions they are able to ask in addition to their primary question.

For example, yesterday National had seven primary questions and 38 supplementary questions – the bulk of which went to Leader Simon Bridges.

The National spokesperson said if the party had accepted the question from the Greens, it would mean it would have had to spread the same amount of supplementary questions over an increased number of primary questions.

This, the spokesperson said, would give MPs less of an opportunity to continue a line of questioning through supplementary questions.