A lot of people seem to think that the Real Estate tax year begins on January 1st. This is not true. In New Hampshire the tax year runs from April 1st of the current year, to March 31st of the following year. New Hampshire sets the new tax rates during the month of October. The bills are then calculated and delivered to the property owners of record. They are due 30 days from the date of the bill. Most towns bill on a semi-annual basis.
If a tax payment is not made when due, interest is assessed at a rate of 12% per annum. Once a property has had a tax lien filed the interest rate increases to 18%. The value of your property is based on the value as of April 1st in any given year.