The Government has been accused of "giving in" to insurance industry lobbying by delaying some of the changes contained in radical new legislation.
The changes in insurance law coming into effect are set to give a massive boost to consumers and small firms.
The new legislation has been described as a "game-changer" by the Alliance for Insurance Reform.
But it criticised the fact that some of the provisions of the new Act, which was introduced by Sinn Féin's Pearse Doherty, are being delayed.
The Alliance claimed: "It is clear that the Government gave in to the insurance lobby."
Finance Minister Paschal Donohoe said after discussions with the insurance industry he believes insurers need more time to get ready for some of the changes.
First introduced in the Dáil in 2017, the provisions of the Consumer Insurance Contracts Act that are coming into force this week are still set to turn the tables on insurers.
They have been described as the most radical shake-up of insurance law in centuries.
"The new laws coming into force today are a radical shake-up of insurance law that will benefit consumers in the years ahead," Mr Doherty said.
He added that the new law will make it more difficult for insurers to refuse paying out on valid claims, and it will shift the balance of power away from insurers and towards consumers in their contracts.
But he criticised the fact some of the provisions of the act have been postponed to next year.
"Despite being signed into law eight months ago, the Government is refusing to commence a number of provisions of the legislation... delaying crucial insurance reform."
Changes that are coming in this week will make it more difficult for insurers to reject a claim. Consumers will have longer to withdraw from an insurance contract, even after accepting documents.
Those with insurance will have to be told if a settlement is being made.
This is a highly contentious issue, particularly when insurers settle spurious claims rather than going through the expense of fighting them in the courts.
This week's changes will put limits on the controversial so-called practice of 'retention', where insurers retain part of a settlement when there is a successful claim.
But put off until September next year is a provision that would stop insurers refusing a claim on the basis of an innocent mistake made by the consumer when applying for cover.
Also deferred is a measure requiring insurers to list premiums paid and claims paid over the past five years.
Peter Boland of the Alliance for Insurance Reform said: "On the specific sections that have been delayed, it is clear the Government gave into the insurance lobby."
He said insurers have known for years these changes were coming.
Asked if he had given in to Insurance Ireland lobbying, Minister Donohoe said insurers need more time to prepare for some of the changes, such as requiring them to list premiums and claims paid in the last five years.