Liam Gilfoyle was put on the Sex Offenders Register for ten years in January 2017, after he was convicted of sexual assault, said prosecutor Kate Beardmore.
As a condition he must notify police of his address every seven days, the court heard, but he missed appointments on September 27 and October 9.
Ian Pridham, mitigating, said Gilfoyle's "very long record" of previous convictions had led to him being homeless "for a very long time."
"He has been signing on each and every week and this is the first time he has breached it," he said.
Gilfoyle, who was on bail at the time, for charges of criminal damage, threatening behaviour and a drugs offence, was also ordered to report to the police station twice a week.
"It never occurred to anyone to tie in the reporting condition and the SOR reporting," said Mr Pridham. "For whatever reason it simply slipped his mind to report on these two days.
"He has effectively been signing on at the police station three days a week."
Gilfoyle, 30, who is currently a serving prisoner at HMP Nottingham, admitted the breach when he appeared, via video-link, at Mansfield Magistrates Court, on Thursday.
He was given a six month conditional discharge and ordered to pay a £21 government surcharge.
For more cases from Mansfield Magistrates Court, click here.