The proposals, published by the Cabinet Office yesterday afternoon, include making all lobbyists pay a flat fee to join the register.
The Act was conceived by the Government to give the public more confidence in the way third parties, such as lobbyists, charities and trade unions, "interact with the political system" and was approved by Parliament despite widespread criticism.
It intends that consultant lobbyists will have to register and disclose the names of their clients as well as declaring whether or not they subscribe to a "relevant code of conduct".
But the Government has said it does not want the cost of the register to be funded by the public purse so, under the proposals, lobbyists will have to pay an annual flat fee to be registered and the registrar, expected to be Royal Mail’s commercial director Alison White, would be able to pursue the fee as a debt if a company did not pay.
The flat fee, which has not been specified, would cover processing applications, staff and IT costs, compliance-monitoring and "enforcement action".
APPC chairman Iain Anderson expressed concern at the proposals, telling PRWeek: "At this stage the consultation is proposing a flat fee – regardless of consultancy size – for funding the register.
"This is likely to be concerning for many of our members. At this stage we will be consulting all APPC members on their views and meeting directly with the Cabinet Office and the newly formed Office of the Lobbying Registrar."
Meanwhile, Francis Ingham, director general of the PRCA, said the proposals raised more questions than they answered.
He added: "The consultation gives our industry the chance to focus our gaze once again on the particular practical muddles this Act brings with it. Is this suggestion of a flat fee to those on the register really an appropriate way of charging consultancies if the price risks being prohibitively high?"
Ingham, whose organisation recently wrote a letter querying a number of aspects of the Act, also questioned whether the Government had a ‘Plan B’ in case a slew of lobbyists refused to join the register "because the definition is so inadequate".
Alastair McCapra, chief executive of the CIPR, described the consultation as a "welcome pause for breath" in the Government’s rush to deliver legislation that would result in "a reduction in openness and transparency for lobbyists".
He added: "Unlike previous consultations on this matter, it is our hope that the Government listens to the experts, and takes their advice and guidance on board, specifically that the cost of registration must not be prohibitive."
The Cabinet Office is consulting on the proposals until 17 October and it wants the register to be in force by 1 January.