National leadership rivals Todd Muller and Simon Bridges top the list of highest-spending non-ministerial MPs, according to the latest list of expenses.

Between January and March 31 this year, Bridges spent $37,200 on his taxpayer-funded credit card.

This is made up of items such as accommodation and travel costs.

Bridges is eligible for VIP transportation services and the spending is $5000 less than over the same period last year.

But Todd Muller, who will tomorrow challenge Bridges for the leadership of the National Party, is spending similar amounts of money to his rival.

He put $34,500 on his credit card at the start of this year – that's more than double the $15,000 he spent over the same period last year.

But since then, Muller was handed National's agriculture portfolio, which entails a lot of travelling to rural parts of the country.

More than $26,000 of his expenses between January and March 31 were on travel, the expense list shows.

Although the MPs' expenses only captures the start of the Covid-19 lockdown, the total amount spent by each party is roughly the same as it was this time last year.

In fact, National actually spent more.

Between January 1 and March 31 in 2019, National MPs spent $979,500 on their taxpayer-funded credit cards, more than the $914,200 the previous year.

For Labour, MPs spent $389,000 at the beginning of last year, compared to $379,000 this year.

Labour's expenses are so much less than National's because many of Labour MPs are ministers and their spending is recorded separately.

The Greens spent $2000 less this year, compared to the $63,700 their non-ministerial MPs spent last year.

But NZ First MPs have been spending up a storm.

Their four non-ministerial MPs spent $72,500 at the start of this year – that's almost $15,000 more than the $59,000 spent over the same period the previous year.