Phishing is the practice of luring unsuspecting Internet users to a fraudulent website in an effort to send future spam.
Officials say no financial or personal information was disclosed because the county does not store that type of information on its online payment system.
However, email addresses and telephone numbers may have been compromised.
Authorities warned the public that if they receive an email or telephone call from a solicitor saying there was a problem with a payment, do not respond or provide any financial information. Instead, contact the Ventura tax collector at (805) 654-3744, or the Ventura County Superior Courts at (805) 654-2965, to validate whether a payment is due.
The sheriff's department also advised the public to contact their financial institution if they notice any suspicious transactions.