CANBERRA, May 21 (Xinhua) -- Australian Prime Minister (PM) Scott Morrison has admitted he is not certain that he will be able to deliver his signature tax cuts before the start of the new financial year.

Morrison on Monday morning promised to take swift action to introduce his promised 158 billion Australian dollars (109.3 billion U.S. dollars) in tax cuts after winning Saturday's general election but by Monday night admitted they could be delayed by a year.

In order to be implemented in time for financial year 2019/20 the cuts must be passed by Parliament before the end of the current financial year on June 30.

However, Morrison must wait until the writs declaring the full election result are returned before he can reconvene Parliament, a process that may not be completed until late June.

"We obviously have to wait for the writs to be returned and there is a formal process for that," he told Sky News Australia on Monday night.

"At the moment, it is not looking like until the back end of June.

"So that really does make very narrow that opportunity to do it before June 30, and I think that is very unlikely with the advice I have received."

The tax cuts were the centerpiece of Morrison's re-election campaign.

Under the cuts, an average dual income household would receive an extra 2,160 AUD (1,494.7 USD) per year.

The government also intends to make it so every Australian who earns between 45,000 AUD (31,140 USD) and 200,000 AUD (138,402 USD) per year is subject to the same tax rate of 30 percent by financial year 2024/25.