It pays for superannuation fund members to take a closer look at their fund's benefits. Few employees realise their company might well have done a deal with a super fund that provides great benefits but should the member change jobs the benefits would cease.

"In most cases these special corporate deals are forfeited when employees leave for another job - the deal being contingent on their continuing to work with the employer," says Andrew Proebstl, chief executive of industry fund legalsuper.

Employees can choose who manages their super but most do not and are happy to be with the fund their employer elects as the default fund.

Corporate funds have all but disappeared and employers now prefer to have their employees' super handled by specialist providers. Michael Rice, a director of Rice Walker Actuaries, estimates that all but about 200 companies now use an industry fund or a master trust as the default fund for their employees.

He says large commercial providers run "sub-plans" with tailored fees and insurance benefits for each employer.

When members in these sub-plans leave their employer, they are often transferred into a personal division of the provider, with a different benefit design and fee structure.

In some cases, a financial adviser is allocated to the member and fees for ongoing financial advice are charged.

The implication for members from the deals struck between employers and super providers behind closed doors are rarely spelled out in a fund's disclosure document.

Competition between providers to become the default fund can work in employees' favour. For example, a provider can extend generous insurance cover to those in the workplace opting to go with the default fund. Also, as part of the deal, the employer might subsidise the administration fees of the default fund.

But few realise that the good deal can end once the member leaves that employer and they find super fees have gone up on changing jobs, Proebstl says.

The deals often extend beyond fees to include insurance. On leaving the employer, members can find they no longer have insurance cover. With no automatic acceptance, the member might have to undergo a medical examination and could be refused cover.

Some employers are handing the super savings of their employees to financial institutions in return for commercial favours. There is talk of banks offering favourable terms on business loans in exchange for making the banks' super offerings the employer's default fund.

That can leave employees, ignorant of the behind-the-scenes wheeling and dealings, in a default fund that is not necessarily in their best interests.

Generally, the default funds provided by larger employers are sound investments. They diversify the money between the major asset classes and are backed by large financial institutions. Multi-employer funds, whether not-for-profit industry funds or commercial (for-profit) master trusts such as those run by banks, insurers and specialist providers, tend to be rated highly by researchers.

However, industry funds usually provide the same benefits to all members regardless of where they work. The commercial providers lean to carving out special deals on a workplace-by-workplace basis.

Super funds are required by law to disclose fees and insurance to employees when they join the fund but most employees do not pay much attention to it.

"As a consequence, most employees won't expect to be hit with higher fees, or to forfeit their insurance when they change jobs," Proebstl says.

"Many employees are under the mistaken belief they will enjoy these corporate deals into the long term, when, in many instances, they won't enjoy them for long at all, and may be upgraded to higher fees more akin to retail fees.

"They are not being told that if they leave the employment of that organisation they will lose access to that deal." Proebstl says super funds should go to extra lengths to provide clearer and more readily understandable disclosure.