A police summary of the offending says: "When spoken to, [Singh] denied making the entries himself and in explanation said that he did complete the community work and that he would leave his sheet for anyone to sign."
After a hearing, Singh was found guilty of a charge of forgery, and jailed for four months.
Senior police prosecutor Sergeant Paul Watkins, who secured the conviction, told APNZ it was the first time he'd seen anyone forge such documents.
Mr Watkins said he was happy with the sentencing, as the public must have confidence sentences imposed by the courts were carried out.
Department of Corrections spokesman Alastair Riach there were checks and balances within the present system, and no changes were made because of Singh's offending.
"Occasionally an anomaly is found through checking processes with appropriate action taken to ensure processes are followed correctly."