Tonga Harris was arrested at a home in Springfield, near Gosford, and taken to Woy Woy police station on Monday morning after an investigation into retirement village residents' bank cards being stolen and bank accounts being accessed.

The Canberra residents were among 15 people police allege were targeted by Mr Harris across many parts of NSW and the ACT, including the NSW Central Coast, the Southern Highlands, the Illawarra and Canberra.

Police allege he stole bank cards through various means, then contacted the victims posing as a representative from their bank. He then used this information to withdraw money from ATMs in nearby areas.

The offences occurred between January and April this year.

The youngest of the victims was 78 years old, but most were aged in their 80s and 90s.

During their search of Mr Harris's home, police seized mobile phones, cannabis, banking documentation and clothing.

Mr Harris appeared in the Newcastle Local Court on Tuesday charged with 19 counts of dishonestly obtaining property by deception, plus possession of a prohibited drug.

He was granted bail by Magistrate Hugh Donnelly, who required him to report to Gosford police station three times a week, plus imposed a condition that he could not leave his home unless in the company of his mother.

Mr Harris will face court next at Moss Vale, in the NSW Southern Highlands, on June 2.

Police have urged members of the public, especially vulnerable people such as the elderly, to never give out their bank or personal details, particularly over the phone.

Police have also advised that if anyone suspected their banking details had been fraudulently obtained, to report it to ACT Policing on 131 444.

ACT police said that criminals often single out the elderly believing they are "soft" targets.