The number of wealthy UK taxpayers admitting to unpaid tax on offshore assets has jumped 35 percent from 3,301 to 4,443 in the last year, multinational law firm Pinsent Masons has discovered.

These figures represent the number of declarations made to the Worldwide Disclosure Facility, a system by which taxpayers owing tax to HMRC on offshore income can come forward and declare.

This allows taxpayers to potentially receive red...