The anti-graft agency sent a 4,000-page investigative report on Ms Yingluck's allegation of dereliction of duty in the rice-pledging scheme to the Office of the Attorney-General that would have a working group reach a conclusion on the case in 30 days.
In this case, Ms Yingluck was accused of negligence of duty and tolerating the scheme, continuing its corruption and causing losses to the state of about Bt500 billion.
Deputy Spokesperson Santhanee Disayabut said the attorney-general will form a special committee to handle the case carefully and quickly.
If evidence is sufficient, the office can file charges with the Supreme Court's Criminal Division for Holders of Political Positions in 30 days.
If it is not, the attorney-general will set up a joint working group with the NACC to work out the case fairly.
Whether Ms Yingluck returns to Thailand or not will not impact the case, Mrs Santhanee said.
On July 17, the NACC resolved unanimously to file its accusation against Ms Yingluck who administered the rice-pledging scheme in her past capacity as the chair of the National Rice Policy Committee.