The 17-year-old pop phenomenon only released her record-breaking debut LP 'When We All Fall Asleep, Where Do We Go?' in March, but her sibling and collaborator has revealed they've already have come up with plenty of ideas for the follow-up whilst on the road.
Speaking to Zane Lowe on his Apple Music Beats 1 radio show, Finneas spilled: "I'm writing the album now and I think the album's all new.
"I think it'll mirror 'When We All Fall Asleep...' in that sense that the EP had 'Ocean Eyes' and 'Bellyache' and then the album was just only album songs and no re-releases so we're excited about that one.
"We're deep into the creative process on new material for sure.
"I think when 'Don't Smile at Me' came out ... And 'Don't Smile at Me' came out August of '17 and the album came out in March 29th of 2019, right?
"But you know, we were percolating that whole time and probably even before the EP was done, 'I Wish You Were Gay' is a song that was written during the recording of 'Don't Smile at Me'.
"So we always kind of have these crossover things.
"But I think the main point of this was that this is an album that we really love to play live and it's continued to grow and that's been a great blessing and we're just excited to play a year on this album that really services this record."
Finneas - who produced the first record - used to be "scared" about working whilst on tour - but now that his sister has a huge team running the ship now, he's able to work on music without any "distractions".
He added: "Also I think the benefit is that because I have found real success in creating while on the road, it doesn't scare me as much the way that I think it used to.
"When we were touring really small scale, your day is so like intense and focused on putting on the show because you're doing everything yourself.
"And I think now that we have such a wonderful expanded team, it allows me to basically wake up in the morning and I have a studio road case in my dressing room and I roll in there and I work for six hours.
"And there's not even the distractions of home to stop me from working.”