Self-invested personal pension (Sipp) provider James Hay saw its assets under administration hit £25bn at the end of October, an increase of 14 per cent on the £22.1bn from last December.
Its parent company IFG Group said the platform had net inflows from new and existing customers of more than £2.1bn in the past 10 months.
Alastair Conway, chief executive of James Hay, said the positive growth has been driven by "more focused relationships with adviser firms and heeding their calls for more streamlined processes".
He cited the developments to the company's digital proposition and the use of e-signatures as examples of this.
Mr Conway said: "We know these improvements all help advisers to deliver a better experience for their clients."
Earlier this year James Hay switched off paper applications for its flagship Modular iPlan products and moved the sign-up process online only.
James Hay's parent company now has more than £30bn in total assets under administration and advice and more than 60,000 customers.
IFG Group is still waiting for a potential sanction from HM Revenue & Customs (HMRC), announced in July.
The company said there have been no developments on this matter since its interim results.
IFG Group has said it is incurring “material” legal and remediation costs in relation to legacy non-standard investments which some James Hay's clients invested in, mainly a structured bio-fuels investment known as Elysian Fuels.
Elysian Fuels was sold as a scheme investing in renewable energy projects in the UK and the US, including in 2013 the launch of a bio-ethanol plant in Grimsby.
About £200m was invested in the scheme - which was marketed as suitable for experienced investors only, with a minimum investment of £50,000.
But investors face heavy losses all after Future Capital Partners, which sold and marketed the scheme, cut the value of the shares in the scheme from £1 each to zero.
James Hay confirmed, at the time, that its clients have invested a total of £55m in Elysian Fuels.
In April 2017 the firm received assessment notices for sanction charges from HMRC for the tax years 2011 to 2012 and 2012 to 2013 in total for £1.8m in relation to Elysian investments.
The Sipp provider has appealed these charges and is in ongoing discussions with HMRC.