The Finance Ministry is demanding 536,986 baht compensation from the PDRC for leading its supporters to trespass on the ministry's compound during their anti-government protest.
Phra Suthep submitted a request for a postponement, saying that he was not yet ready.
The court allowed him a 15-day extension, acepting the former PDRC leader's assurance he had no intention to drag the case out.
Viroj Phumsirisawat, a PDRC lawyer, said his team would submit the defence statement within the deadline.
The Civil Court scheduled Sept 29 for both sides to submit their lists of witnesses to testify in the trial, without requiring the presence of Phra Suthep.
Earlier today, Phra Suthep appeared before the Criminal Court along with former prime minister Abhisit Vejjjajiva in a criminal case filed by the prosecution in connection with the military crackdowns on the red-shirt protesters in 2010 for verification of related documents and evidence.
The prosecution earlier filed two separate lawsuits against them. The Criminal Court, at the defendants' request, agreed to combine the two lawsuits as one.
The case was adjourned to Aug 28.