The Personal Finance Society's paper on VAT and Adviser Charging contains a "significant error" and must be "urgently revised", warns a pension expert.
Her Majesty's Revenue & Customes (HMRC) is to repay an adviser £259,000 for incorrectly charging VAT on intermediary services.
Treasury minister David Gauke has said it is "morally wrong" to pay tradesmen in cash, in the hope of avoiding tax.
Advisers have been warned not to mislead and confuse HMRC by claiming to offer investment management services - a VAT chargeable activity - while lacking the necessary permissions to do so.
The European Court of Justice (ECJ) has said discretionary portfolio management should not be exempt from VAT.