AJ Bell has called on the Treasury to commit to a 'pension tax lock' in the Autumn Budget after a slump contributions in recent weeks. 

The investment platform told investors on Thursday there had been a 'noticeable change in both customer contributions to pensions and tax-free cash withdrawals' ahead of the 30 October budget

Boss Michael Summersgill said AJ had made 'representations' to Rachel Reeve's department in a bid to guarantee 'stability in key pension tax legislation for at least this parliament'.

Under current rules, savers receive pension tax relief at their income tax rate. 

Basic rate taxpayers receive relief at 20 per cent, while higher and additional rate taxpayers receive 40 and 45 per cent respectively.

Rachel Reeves is expected to consider a proposal by Treasury officials for a flat 30 per cent rate of pension tax relief. 

The Treasury could also look to restrict people’s entitlement to tax-free cash when they access their pension pot.

Another potential target is pension pots, which fall outside of the inheritance tax net. 

Summersgill said: 'Pensions are the primary retirement savings vehicle in the UK and customers are unsurprisingly sensitive to changes in their tax treatment. 

'Amidst increased press coverage ahead of the upcoming Budget, we have seen a noticeable change in both customer contributions to pensions and tax-free cash withdrawals.

'Whilst these behavioural changes do not have a material impact on AJ Bell's business performance, they represent significant decisions for individual customers.' 

In its year-end trading update published on Thursday, AJ Bell announced that investors using its platform deposited £6.1billion with the group in the last year, amid a 14 per cent increase in customers. 

AJ Bell saw inflows rise 45 per cent from last year, bringing total platform assets under management to £86.5billion, above Investec forecasts. 

The group said: 'Gross and net inflows across the platform were significantly higher than prior year, driven by the continued investment in AJ Bell's brand and propositions alongside improved retail investor confidence compared to the prior year.'

Summersgill added: 'Our strategy is centred on our dual-channel platform which serves both the advised and [direct to consumer] platform markets using a single technology platform and single operating model. 

'This maximises our growth opportunity within the platform market, whilst being highly efficient to operate.'

Investec analysts said: 'Given the outperformance delivered by both Quilter and IntegraFin during the quarter, we believe that AJ Bell’s in-line performance may be seen as a slight negative.'

AJ Bell shares fell 1.51 per cent or 7.25p to 473.75p on Thursday, having risen over 80 per cent in the last year.