Taxes should be refunded with interest from the taxing authority for which the taxes were levied.
In accordance with A.R.S. §42-18052, one-half of the amount of taxes on real and personal property is due on October 1, and the remaining one-half of the taxes is due on the following March 1. Taxes due on October 1 become delinquent after November 1 at 5 p.m., and taxes due on March 1 become delinquent after May 1 at 5 p.m. If the total amount of taxes is $100 or less, the entire amount is due on October 1; the entire amount that is unpaid is delinquent after December 31 at 5 p.m. If the delinquency date is a Saturday, Sunday, or other legal holiday, the time of delinquency is 5 p.m. on the next business day.
When a county treasurer offers tax liens for sale for the purpose of collecting delinquent property taxes, the treasurer calculates the taxes due, penalties, charges, and the interest on the amount due through February, the month of sale. The successful purchaser of a lien is the person who pays the whole amount of delinquent taxes, interest, penalties, and charges due on the property and offers the lowest rate of interest not to exceed 16 percent. When property owners redeem liens, the treasurer calculates the interest accrued on the liens; the property owners pay the liens’ purchase price plus the accrued interest; and the treasurer forwards the amounts collected to the lien holders in satisfaction of the liens. Interest should begin to accrue in March, not February, and a partial month is considered a whole month for the purpose of this calculation.
For example, for a tax lien purchased in February and redeemed any time in May, a county treasurer should collect the lien’s purchase price plus interest for the months of March, April, and May from the property owner who is redeeming the lien. This answer is based on an Arizona Court of Appeals decision in Ulan v. Pima County Bd. of Supervisors, 213 Ariz. 553, 145 P.3d 650 (October 31, 2006).