In a statement made today, the PFRA confirmed that a transfer agreement had been approved by the its board and members would be asked to ratify the merger at a reconvened annual general meeting on 16 August.
A vote had originally been scheduled for 15 June, with the merger expected to be completed by the end of July.
But the vote was delayed while the legal requirements of the due-diligence process were completed.
Today’s statement said: "The boards of both organisations remain entirely committed to merging and will be encouraging all members to vote in favour. Following the vote at the AGM, we would expect the merger to be completed by 31 August."
Both membership bodies have previously confirmed that there would be no redundancies because of the merger, with the seven existing PFRA staff taking up new positions in the IoF.
Peter Hills-Jones, chief executive of the PFRA, will become the IoF’s director of fundraising compliance.
In March, the IoF and the PFRA confirmed some of the terms of the agreement between the two membership bodies, although full details were withheld because of commercial confidentiality.
The main points in the initial agreement included the creation of three new sub-committees of the IoF board, focusing on door-to-door fundraising, street and private site fundraising, and telephone compliance.
PFRA reserves and assets will be transferred to the IoF and ring-fenced until the end of July 2019 for the purposes of "supporting and furthering compliance in public fundraising", according to the initial agreement.
The agreement also confirmed that the IoF would appoint a trustee from a public fundraising agency with expertise in fundraising compliance.