A couple of weeks ago, the ACB had recorded a detailed statement of Mr Mishra and was to question him last week but he had sought deferment of his questioning for the day due to personal reasons.
He was supposed to appear for questioning on today but due to some reasons, he couldn't appear on today. He will be questioned tomorrow, said a senior ACB officer.
Delhi Chief Minister Arvind Kejriwal's private secretary Bibhav Kumar was questioned last week by the ACB in connection with the "scam."
Mr Mishra had alleged that Mr Kejriwal had "influenced" the probe into the tanker scam that dates back to Sheila Dikshit's tenure as chief minister.
The Kejriwal-led AAP government had in June 2015 constituted a fact-finding committee to go into the alleged irregularities in procuring some 385 stainless steel water tankers by the Delhi Jal Board.
The Delhi government in June 2016 had sent a report of the fact-finding committee to erstwhile Lt. Governor Najeeb Jung following which an FIR was registered in the case.