Those who have set up their own schemes using an insurance company, bank or other provider may be the legal administrator themselves, HMRC says.

This role carries a number of legal responsibilities, including making information returns to HMRC and paying certain tax charges if they arise. HMRC has produced a factsheet covering these responsibilities in more detail.

An HMRC spokesman said:

"Even the smallest pension scheme must have a scheme administrator, and they need to be aware of their responsibilities. If you're not sure who this is, find out now, to avoid any problems in the future."