A doctor posted to Changi General Hospital (CGH) reported sick on Nov 20, 2015, so he could work as a locum at a private clinic instead.
Five days later, Joel Arun Sursas forged a medical certificate (MC) for his purported sick leave.
On Wednesday, Sursas, 28, pleaded guilty in court to one count of forgery. Three other charges for similar offences will be considered during sentencing.
Deputy Public Prosecutor Ben Mathias Tan told District Judge Mathew Joseph that Sursas had worked at CGH's diagnostic radiology department between Sept 1, 2015, and Jan 4, 2016.
He worked as a locum, or stand-in doctor, at Etern Medical Clinic on 47 separate occasions between July 10 and Dec 11, 2015.
The court heard that after reporting sick on Nov 20, Sursas worked at the clinic from 6.30pm to 9.30pm, earning $95 an hour.
Court documents did not state the exact location of the clinic where Sursas had worked as a locum. Etern has branches at locations such as Sengkang and Punggol.
On Nov 25, 2015, Sursas wrote himself an MC and created a false impression that a locum at Etern had signed it. He later submitted the forged MC to CGH.
The DPP said: "By forging and backdating the forged MC in this manner, the accused was in breach of his professional duties owed as a doctor... The offence was difficult to detect and was only uncovered when CGH made inquiries with Etern."
What Joel Arun Sursas earned an hour working as a locum at Etern Medical Clinic.
The Straits Times reported in October last year that the Singapore Medical Council's (SMC) disciplinary tribunal found Sursas guilty of working as a locum on 47 occasions, issuing MCs to himself in such a way as to give the impression that they had been issued by another doctor, and backdating one of his certificates.
The tribunal suspended Sursas for three years, imposed a $15,000 fine, censured him and ordered him to pay the cost of the proceedings.
Sursas had been granted temporary registration in May 2015 to be employed by the Ministry of Health Holdings (MOHH) and to work in an institution approved by the SMC.
The MOHH terminated Sursas' employment in January 2016 after his actions were uncovered. The SMC also cancelled his temporary registration, which meant he could no longer practise here.
However, as Sursas is no longer a registered doctor, the tribunal's decision to suspend him is moot.
Sursas' bail was set at $5,000 and he is expected to be sentenced on May 7. Offenders convicted of forgery can be jailed for up to four years and fined.