The controversial APN regime means that HMRC can demand tax it believes it is owed before the dispute is adjudicated. Those affected only have 90 days to pay the sum, and have no right of appeal.
Earlier this year, the Revenue backtracked 2,000 APNs because conditions for their issuing were not satisfied.
In February, HMRC said it had collected more than £2bn from disputed tax and tax avoiders since the first APNs were issued in 2014.
RPC challenged HMRC on a number of grounds, including that the Employee Benefit Trust arrangements under consideration were not "notifiable" to the Revenue under the DOTAS regime.
The firm said HMRC has now admitted that it did not have the right to issue the APNs related to those arrangements.
Adam Craggs, partner and head of tax disputes at RPC, said, “HMRC’s policy of issuing accelerated payment notices seems to be ‘shoot first and ask questions later'.
“It is regrettable that the taxpayers concerned were put to the inconvenience and expense of having to commence judicial review proceedings before HMRC acknowledged that the APNs were unlawful."
An HMRC spokesperson said, “We don’t comment on individual cases. There is no mass withdrawal of APNs. We have withdrawn accelerated payment notices from schemes where their promoters brought them to our attention when they did not legally have to. We have issued over 50,000 such notices and collected over £2.5billion for the UK.
"Just because a notice has been withdrawn it doesn’t mean there is no tax to pay. The underlying tax dispute remains until it is settled or taken to court.”
However, Craggs said HMRC “appear to be issuing APNs on an industrial scale with little consideration to the constraints contained within the legislation” and warned APNs can result in taxpayers being made bankrupt or being forced to conduct a fire sale of their home or other assets to pay the sum.
“There were repeated warnings from many in the tax profession when the Accelerated Payment Notices legislation was announced that there were insufficient safeguards for taxpayers and the lack of independent judicial scrutiny was a concern to many.
“As this case demonstrates, any taxpayer in receipt of an Accelerated Payment Notice should not assume that HMRC has followed the correct internal processes and exercised its powers lawfully,” he added.