Xafinity is warning that thousands of SSAS trustees could face fines from HM Revenue and Customs if their SSAS has been managed incorrectly.
The firm said it had seen many enquiries from SSAS trustees where the SSAS has not been administered by a specialist pension professional.
The need for an independent pensioneer trustee was removed in 2006 and replaced by an administrator who was responsible to HMRC for the running of the scheme.
This meant some SSASs had since faced issues such as non-submission of pension scheme returns, loans made without the required security, sponsored employers ceasing trading and members wanting to take benefits.
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These problems can lead to significant tax charges and fines and lower pension values at retirement.
In June 2013, HMRC levied a £55,000 tax charge after a SSAS made an unsecured loan to the sponsoring employer.
Jeff Steedman, Sipp and SSAS business development manager at Xafinity, said: "Recent HMRC action demonstrates a change in attitude and while historically HMRC may not have been proactive on these scheme they appear to be sharpening their focus.
"A 55 per cent tax charge could devastate members' retirement funds and could potentially be avoided with a regulatory change to require a professional administrator.
"The DIY approach to SSAS administration was a mistake and HMRC needs to introduce the requirement for a professional SSAS Administrator for all schemes."