Land Tax relates to land you own as at midnight on the 31st December each year, but excludes your principle place of residence. You should note that it is the unimproved capital land value (ie. without a house) that is used to calculate the land tax. You will find the value of your unimproved capital land value in your Council Rate notice.
To find out your Land Tax payment, if any, please visit the The Office of State Revenue : www.osr.nsw.gov.au/taxes/land