The pensions system has gone through some significant changes
Experts have criticised fresh changes to the pension system for adding a greater burden to employers running schemes.
Chancellor Alistair Darling announced moves to prevent people with incomes of over £130,000 putting huge sums into their pension funds to gain tax relief.
There are varying conclusions about how many people will be affected.
But many commentators said that the added complication would accelerate the number of workplace schemes being shut.
In his Budget in April, Mr Darling said that the government intended to restrict tax relief on pension savings for those earning more than £150,000.
The changes are planned for April 2011, so he also brought in rules - known as anti-forestalling measures - to prevent people putting lots of their earnings into their pension pot in the meantime.
But now the floor for the restriction of tax relief has shifted to £130,000 if they change their normal pattern of pension contributions.
This could have a particular effect on company owners who were planning to pay themselves between £130,000 and £150,000 this year in light of the Budget announcement, or companies having to administer in-house pension schemes.
Martin Bird, principal consultant at Hewitt Associates, estimated that an additional 70,000 individuals would be affected, and it would add significant complication to an already complex system.
"The government is introducing more obligations on employers, scheme administrators and trustees, all of which will add to the costs of running schemes. Once again, pensions simplification is right out of the window," he said.
Pension scheme threat
Marc Hommel, partner at accountancy firm PricewaterhouseCoopers, said: "In the weeks following last April's Budget, over three-quarters of employers said that the government's pension tax proposal for higher earners was further reducing companies' motivation to provide wider workplace pensions.
"Today's announcement that employer contributions will now also be included in higher-rate tax relief restrictions for people earning £130,000 or more, together with the associated administrative complexity, will result in further acceleration of scheme closures."
Tom McPhail, of Hargreaves Lansdown, said that the change announced in the pre-Budget report was primarily a technical correction that would not bring in any significant extra revenue. He agreed that it would create extra complication to the system.
He pointed to other changes in the pre-Budget report that would encourage lower earners to withdraw cash from their pension pot if they were only in a scheme for a short time, rather than leaving it until their retirement.
Tax was previously deducted a 20% on the first £10,800 withdrawn, and at 40% thereafter. The chancellor plans to tax the first £20,000 at 20% and then at 50% thereafter.
Separately, the roll-out of a proposed system that will see workers automatically enrolled into a government-backed workplace pension scheme, if they do not already have access to one, will be extended. The system, which includes Personal Accounts, will be introduced between 2012 and 2017 - not 2016 as previously planned.
Higher earners in the public sector are likely to carry the burden of changes to pension schemes for employees in schools, local government, the NHS, and the civil service.
In March 2008, the Government Actuary's Department estimated that if the various pay-as-you-go public sector schemes were financed by investment funds, rather than being paid for directly out of taxation, they would need assets worth £770bn.
Although details are relatively thin, the government plans to introduce a cap at which point the employer - funded by the taxpayer - will stop making pension contributions.
Cost increases above this cap will be funded solely by employees putting more into the pension pot or seeing their benefits for future service reduced, or both.
The maximum limit of employer contributions will be assessed every three to four years.
"The government will expect those earning the highest salaries to pay a greater contribution towards their pension," the pre-Budget report papers explained.
The government believes that these changes will reduce the bill to the taxpayer by an estimated £1bn a year from 2012-13, and at double this amount in the long-term.
There has been considerable debate about the relative generosity of public sector pensions, compared with the private sector where many schemes have shut to new and existing members.
Public sector unions say that a good pension is part of the deal as wages are lower.