Liam Payne and Louis Tomlinson are One Direction's richest members.

The two singers have a number of writing credits on the band's songs and as a result, it has been widely reported that the duo have been cashing in via royalties.

The pair, for example, worked on the band's recent tracks 'Midnight Memories', 'Diana' and 'Better Than Words'.

Speaking to The Sun, Payne confirmed that he and Tomlinson have formed a writing "partnership", saying:

"Louis and I have a little partnership going on. We've been pretty keen to start writing straight away. I've been in the studio already, it's been going really well. Learning how to write is the best way of ensuring your career has longevity and that you have control over it."

He added: "I really think the next album is going to be a game-changer for us."

Watch One Direction's recent videos below: