"Taxi" is an unreleased song by SOPHIE featuring Charli XCX. It was intended for Charli's original third studio album concept but was never going to appear on it, confirmed by Charli in November 2016. The track is considered one of Charli's most infamous and popular unreleased tracks, and she is still frequently asked to perform it years after the initial performance.
The song was written with Klas Åhlund and Noonie Bao, presumably at the same session as "Bounce", "Roll With Me", and "Round & Round". Two years after its debut performance at Exchange LA 2016, Charli performed the song at the Pop 2 London show in June of 2018. The demo of "Taxi" was leaked on SoundCloud during September 2018, to celebrate the 2 year anniversary of the "After the Afterparty" release.
Charli teased the song on Twitter in April of 2019, stating "imagine if I officially released taxi... you guys would have nothing left to tweet at me".
During June of 2019, SOPHIE played the full final version of the song at her live show. A full live recording is yet to surface.
On October 21st, 2019, Charli played "Taxi" at the NYC show from the Charli Tour in the pre-show. The version she played was in high quality, had reworked vocals, and was pitched down. When asked why she did it the next day in her Instagram Live, she responded saying, "Because I'm a troll, that's why".
She played the new version of the song again for her live DJ Set on March 25, 2020, and once more during 100 Gecs' Square Garden Minecraft concert on April 24, 2020.
- September 23rd, 2018 - The full demo of the song leaks in high quality on Soundcloud. 
- March 25th, 2020 - The final version of the song leaks in full and high quality online. 
- November 6th, 2021 - Lossless demo of the track leaks online. 
- November 16th, 2021 - Stems of the track leak online. 
- On a live performance in June 2, 2019 she joked about playing Taxi right there, and immediately take it back saying "I'm gonna play that song in my funeral the day I die, or if SOPHIE wants to release it". Stating that she probably won't release Taxi herself ever. 
- On an interview with Gay Times, while having a conversation, Troye Sivan brought up the joke about releasing the song: "Your fans want me to ask... When are you going to release Taxi?", for what Charli answered, "Oh my god, Troye. Shut up."