Decide the rules and then leave them alone for at least 10 years, the government is told

The boss of a leading financial adviser has made a direct appeal to the government to "simplify and stabilise the UK savings system".

Andy Bell, the chief executive of AJ Bell, wrote to both chancellor Philip Hammond and pensions minister Richard Harrington to urge them to set up a new independent pensions tax commission whose recommendations would be set in stone for at least 10 years.

"Over the years the two most popular saving products, namely pensions and ISAs, have become incredibly and unnecessarily complicated through waves of changing legislation. This at best confuses savers and at worst discourages people from saving at all."

Bell added that on the run-up to the government's annual budget and autumn statement announcements there is a lot of speculation on the changes that may be afoot. He said: "Such speculation is not well-informed and undermines trust in the stability of the system."

The proposed commission would establish what changes needed to be made to pension tax relief. Its "recommendations could form the basis for a lasting, cross-party settlement".

The letter follows reports that the government is planning a shake-up the pension tax relief system in this November's autumn statement.

Experts disagree on what exactly needs to be done. Some, such as Tom McPhail of Hargreaves Lansdown, advocate a tax relief structure linked to age that would provide a greater incentive to younger generations to save for later years. Others, including former pensions minister Steve Webb, have advocated a "no change" policy.

Fiona Tait of Royal London has also urged the government not to tinker with the system. "Age-related tax relief might provide an incentive for younger savers but could hinder understanding and appreciation of the tax incentives for the population as a whole," she said.