The Central Bank has confirmed it will ease its proposed mortgage borrowing limits for first-time buyers.

It's published the long-awaited details of its new limits for mortgage lending this evening - but the proposals will need new laws to take effect.

As originally proposed, most mortgages will require a 20 per cent deposit - but some wriggle room has been built into the system for first-time buyers.

They will be allowed be able to borrow up to 90% of a property value, up to a cap of €220,000, and 80 per cent of the rest.

Buy-to-let purchasers will meanwhile have to come up with 30 per cent of the purchase price themselves.

This means that a first-time buyer wishing to buy a 3-bedroom house in Dublin - which would currently cost €350,000, according to Daft.ie - would now be able to borrow €302,000, rather than the originally planned limit of €280,000. They would have to come up with the other €48,000 themselves.

But in a crucial limit, all mortgages are limited to 3-and-a-half times the buyer's total income.

The rules mean that the first-time buyer who needs to borrow €302,000 for a home in Dublin will need an annual income of over €86,000 in order to borrow the remainder.

Both the Government and the Central Bank say the measures will protect both borrowers and banks.

"Although they have been designed to be stable, the requirements are flexible enough to be adjusted in the future should the need arise without the need for a long period of consultation," Central Bank governor Patrick Honohan said in a statement.

Michael Noonan - who appears supportive of the new rules, after his Department criticised the original plans - said the "revised proposals will provide certainty to borrowers and ensure that banks continue to engage in prudent lending practices."

The minister said he would be tabling new laws before the Oireachtas to give effect to the proposals - meaning political approval will now be needed from within the Fine Gael and Labour ranks to get the laws approved.