Waiting lists for routine surgery have risen by up to 50% in parts of the country because senior doctors say they cannot afford to work extra shifts.
Consultants have begun refusing to work beyond their planned hours after receiving unexpected tax bills, following new pension rules in 2016.
NHS hospitals said delays are becoming increasingly routine as a result.
The Department of Health said it aimed to solve the problem with more flexible pensions.
Consultants who earn more than £110,000 a year faced new limits on how much they could contribute to their pension from 2016. Complex rules mean the charges can be unpredictable if they go over the allowance.
But those near the threshold have have few options to avoid the impact, other than reducing their hours, quitting the NHS pension scheme or taking early retirement.
NHS Providers, which represents hospital trusts, said senior staff were now saying they could not afford to work at weekends to bring waiting lists down.
A senior anaesthetist at one hospital worked 27 Saturdays last year to reduce waiting times but now cannot afford to, the organisation said.
Another hospital has seen numbers waiting for routine surgery increase by 50% since April, with staffing issues due to the pensions problem partly to blame.
The Guardian reported that the Royal Bournemouth Hospital has 53 sessions of surgery and 150 procedures uncovered between now and 27 July because no consultant anaesthetists are available.
NHS Providers said a solution is needed urgently and the government is moving too slowly.
The Department of Health said it wanted to make pensions more flexible, so senior doctors would be able to reduce their contributions and avoid breaching the allowance.