The Scissor Sisters star and the 71-year-old music legend - who composed 'Billy Elliot the Musical' and is working on a remake of 'The Lion King' with Tim Rice - have been secretly working on a stage show together and having a ''joyful'' time in the process.
However, it could be some time before the fruits of their labour are on the West End or Broadway.
The 'I Don't Feeling Like Dancing' hitmaker told the Daily Star newspaper: ''Musicals take forever to get made, it's a long-ass time because they're so complicated.
''I'm really excited about it. Me and Elton hole ourselves up for days at a time, and just laugh. Then we write, then we laugh, then we write. All my experiences with Elton creating are joyful.''
Jake - who releases his self-titled debut solo album on Friday (10.08.18) - previously starred in Broadway's 'Kinky Boots', which was challenging for the singer.
He admitted: ''I learned that the key to musicals is their structure.
''Getting a musical right is like doing a Rubik Cube.''
Despite finding the experience ''daunting'', Jake recently admitted he'd love to star in another musical.
He said: ''There was so much at stake. I just absolutely gave it my everything. It was immensely satisfying and I did about 100 shows.
''I miss it -- I miss the people, the performances, the show. I loved it and would do it again in a heartbeat. It really inspired me in a lot of ways. I thought I was going to keel over by the time I finished.''
As for reuniting with Scissor Sisters, the 'Filthy/Gorgeous' hitmaker revealed he would love to celebrate the 10th anniversary of their debut LP 'Night Work' in 2020.
The 39-year-old singer says another way he and his bandmates - Ana Matronic, Babydaddy, Del Marquis and Randy Real - could celebrate is by releasing an album featuring songs that were scrapped when they were making the record, which he feels are worth seeing the light of day.
He said: ''I would really love to do a Night Work 10th anniversary record (in 2020). There is also an entire record that we just scrapped and there are some amazing songs.
''I would love to put that stuff out in the next couple of years. It is a lot of fun and the fans will love it.''
Scissor Sisters went on an indefinite hiatus in 2012, after the release of their fourth studio album 'Magic Hour'.