Go to the municipality and check there. If they show they haven't been paid, then go to the County records. Some lenders don't pay on time from the escrow accounts and they may have been paid. If you are purchasing, your title company will make sure all taxes are paid the day they transfer the deed.
Or if they have a website you can log onto the county website and in most larger counties this information will be posted there. You should also find interesting information such as the assessor's tax appraised value (usually quite a bit lower than the true market value though) as well as what the current owners originally paid for the property.