Among the most common likely problems will be the failure to give members the option to nominate trustees, to appoint auditors to pension schemes, maintain up-to-date accounts and keep separate bank accounts for trustees.
Johnstone Douglas, a pay and benefits firm which advises companies on how to convert their pension funds from final-salary to money-purchase schemes, yesterday blamed lack of time for the problem.
But Doug Johnstone, the company's managing director, added that he was concerned at the low levels of understanding by many firms of the changes that need to be implemented when the Pensions Act comes into force.
He said: "From our own experience, we believe that almost 90 per cent of small and medium-sized firms have not yet taken advice on the implications of the new legislation, and simply do not understand what needs to be done.
"There is a real danger that they are going to fail to comply by default. This will potentially affect many thousands of members of company schemes."
The deadline next April follows the passing by Parliament of the 1995 Pensions Act, sparked by the disappearance of more than pounds 400m in pension funds belonging to past and present staff of companies owned by Robert Maxwell, the former media tycoon. His death in November 1991 and the hunt for the missing money sparked the Government's pension reforms.
The new Pensions Act, which many experts point out would not have prevented the Maxwell pensioners' money from disappearing, nevertheless imposes onerous conditions on new pension schemes.
Among the changes required under the Act are new requirements for contracting out of the State Earnings-Related Pension Scheme, or Serps.
Company pension schemes will also be required to pay a levy to cover the cost of the Occupational Pensions Regulatory Authority (Opra), the funds' watchdog, together with financing the new compensation scheme. The maximum cost for existing members of company schemes was recently set by the Government on a sliding scale whereby smaller schemes pay more.
In 1997-1998, the annual levy for the regulator will cost between 8p per member in schemes with 10,000 or more members, rising to pounds 1.05 per person for schemes between 12 and 99 members. The maximum compensation levy will be 23 per person a year.
Oliver Heald, the Social Security Minister who announced the charges, said: "I believe we have struck the right balance between the security for each scheme and costs that come with that security."
However, the Act has been criticised for the unnecessary expense and bureaucracy involved in administering it, plus a new minimum funding requirement, which some experts predict could lead to higher employers' contributions.
Despite recent government figures showing that few firms have so far switched out of complicated, and potentially expensive, final-salary pension schemes, experts believe the trickle will turn into a flood after April, when the Act comes into force.
Mr Johnstone said: "There is a real danger [firms] are going to fail to comply [with the Act] by default and Opra may then step in to impose fines."