Cavendish was filming with the BBC on Mount Etna in Sicily ahead of May’s Giro d’Italia last year when the breach occurred.
The 26-year-old Manxman said in a statement: “I missed an out-of-competition test last April, it was my mistake. I was with a film crew from the BBC and Giro d’Italia on Mount Etna. It was a simple, genuine admin error.
“Of course, I totally understand the importance of testing in sport. I was tested by the UCI [International Cycling Union] a couple of weeks before that and twice in the fortnight after and had around 60 tests in all last year.
“It’s part of the job. And it’s my job to make sure that I don’t miss another.”