The three-week extradition hearing had been due to start on August 6.
However, the office for Dotcom’s New Zealand-based defence lawyer, Paul Davison, told AAP the hearing has been postponed till March 25.
The delay prompted Dotcom, 38, to launch an online attack against the United States and New Zealand governments on Tuesday.
He said on the social networking site Twitter: “Extradition hearing delayed til March. Dirty delay tactics by the US. They destroyed my business. Took all my assets. Time does the rest,” he tweeted.
“The NZ government is refusing a NZ resident due process and a fair defense. Shame on you John Key for allowing this to happen. Shame on you.”
US authorities are trying to extradite Dotcom and three others to face racketeering, copyright and money laundering charges. They face up to 20 years in prison if convicted.
Last week, prosecutors acting on behalf of the US government appeared in the high court to appeal against a district court ruling that Dotcom and his co-accused must be granted access to the evidence held against them for the extradition hearing.
The outcome of that appeal is still unknown.
Late last month, a high court ruling declared an armed police raid on Dotcom’s Auckland mansion in January illegal.
Justice Helen Winkelmann said the search warrants were too broad and police exceeded their powers in seizing what they did.
She also said it was unlawful for copies of Dotcom’s computer files to be taken by US authorities and New Zealand police should return copies to Dotcom.