The Rolling In The Deep singer made a return to music last month (Oct15) after taking several years off to start a family, and her new album 25 is set to become the biggest-selling release of the year (15).

It has now emerged Adele earned a fortune during her time off as she raked in royalties from her previous album 21 and her 2008 debut 19.

Figures from officials at Britain's Companies House show Adele's firm Melted Stone made just less than $27 million (£17 million) in 2014, meaning the singer brought in around $73,000 (£46,000) per day without playing any shows or releasing any new music.

Adele is said to be one of the richest Britons under 30 with an estimated fortune of around $80 million (£50 million), which is set to be given a major boost by sales of 25 following its release this month (Nov15).

The album is already breaking records, and is estimated to have clinched a title held by boyband 'NSYNC for 15 years. The pop group's second studio album, No Strings Attached, debuted in 2000 with first-week U.S. sales of 2.4 million, and 25 has matched the figure in around three days.

Adele's 25 is predicted to shift 2.9 million units in the U.S. in its debut week, with experts suggesting that 42 per cent of all American record buyers have picked up a copy, and she has already received congratulations from members of 'NSYNC.

"Records were made to be broken," says JC Chasez. "It was a flattering luxury knowing we sold more records than anyone in a week but it's also nice seeing people continue to be passionate about music in the next generations. Adele proves that emotion and art are alive and well in music today."

"We officially say Bye Bye Bye as @Adele says Hello to the World Record of Most Albums Sold In a Single Week. Congratulations!!" his bandmate Lance Bass tweeted.

"With technology and current music business model, I thought this one (record) would be tough to beat," Joey Fatone tells Billboard. "In all honesty, Adele is the truth - kinda excited a rare talent like hers is in the same breath as our group. I'm a huge fan... I even bought the damn album!"