Noddy Holder considers 'Merry Xmas Everybody' to be a "nice pension plan".
The 75-year-old star released the festive single with Slade in 1973 and Noddy has likened its impact to "having a hit record every year".
He shared: "I can’t put a figure on [how much he makes], because it’s just different every year. Some years it’s used in an advert or movie. There’s been all sorts of cover versions, from the Spice Girls, Tony Christie and Oasis.
"I’ll get my annual PRS [Performing Right Society] statement and the cross-section of artists who perform it on their Christmas tours is amazing. All four of the original Slade share performing rights but it just happens that Jim [Lea] and me were the main writers, so we earn more."
However, Noddy is determined to remain tight-lipped about the exact amount he makes from the record.
Asked to put a figure on its worth, he told the Guardian newspaper: "It’s like having a hit record every year. So it’s a nice pension plan, I’ll say that."
Noddy also recalled writing the iconic festive tune after spending a night in a pub.
He shared: "Jim’s mother-in-law said: ‘How come that you’ve never written a song that could played every year for a birthday, Christmas or Valentine’s Day?’ The first song I’d ever written, in 1967, was this hippy, psychedelic song called 'Buy Me a Rocking Chair to Watch the World Go By', but the rest of the band said it was rubbish.
"Jim had this melody knocking around, so he put my hook and chorus into his verse and played it to me round his house. That night, I was drinking with the locals and my best mate, our tour manager, Graham Swinnerton – Swinny – at this jazz pub called the Trumpet in Wolverhampton. I went back to my old bedroom at my mum and dad’s, rather merry, and wrote the lyrics in one go."