Idaho property tax due dates give you two choices: pay the full year by December 20, or split the bill into two halves due December 20 and June 20 of the following year.1Idaho State Legislature. Idaho Code 63-903 – When Payable Miss either date and you owe a 2% late charge plus 1% monthly interest on the unpaid portion, with the interest on a late second installment reaching back to January 1 of that year.2Ada County Treasurer. Important Tax Dates
The Two Payment Options
You can pay the full amount by December 20 of the year the taxes are levied. Or you can pay in halves: the first half by December 20 and the second half by June 20 of the following year.1Idaho State Legislature. Idaho Code 63-903 – When Payable
The installment option isn’t automatic. Paying the first half on time by December 20 is what keeps it available. If you miss that first deadline, late charges and interest apply to the unpaid first half right away, and you don’t get a grace period simply because you intended to split the bill.1Idaho State Legislature. Idaho Code 63-903 – When Payable
When December 20 or June 20 lands on a weekend or holiday, the deadline moves to the next business day.3Idaho State Tax Commission. Assessor’s Calendar
When Your Bill Arrives
County treasurers typically mail tax bills by the fourth Monday in November, giving you a few weeks before the December 20 deadline.4Elmore County. Payment Due Dates The bill shows your parcel number, the levy rate, exemptions applied, and the total owed. Keep the notice: every payment method asks for the parcel number.
If your bill hasn’t shown up by late November, call your county treasurer for a duplicate. Idaho law is explicit that failure to receive a tax notice does not excuse you from paying on time, and late charges apply even if the bill never reached your mailbox.4Elmore County. Payment Due Dates
How to Pay on Time
By Mail
Mail a check or money order to your county treasurer. Idaho treats the U.S. Postal Service cancellation mark as your official payment date, so a letter postmarked on or before December 20 or June 20 counts as on time even if the treasurer opens it days later. A postage meter stamp does not qualify.5Idaho State Legislature. Idaho Code 63-217 – Filing of Material by Mail If you’re mailing near the deadline, take the envelope to the counter and ask for a hand cancellation.
Online
Most Idaho counties accept online payments through secure portals using a parcel number and either a credit card or electronic check. Save the confirmation receipt. Some counties pass credit card processing fees along to you.
In Person or Drop Box
County treasurer offices take payments in person during business hours, generally Monday through Friday.6Idaho County. Property Tax FAQ Many counties also keep a drop box at or near the courthouse. On deadline day, drop boxes typically close at 5:00 p.m. sharp, so don’t cut it close.7Latah County Treasurer. Tax Payment FAQ
If You Have a Mortgage Escrow
If your lender collects property tax with your monthly mortgage payment, it pays the county directly when taxes come due, and you generally don’t need to act on December 20 or June 20. Verify it happened anyway. Your county treasurer can confirm whether the account shows a payment, and supplemental or special assessments issued outside the normal cycle are often not covered by escrow and get mailed straight to you.
What Late Payment Costs
Miss a deadline and a 2% late charge is added to the unpaid portion, with interest accruing at 1% per month on the delinquent amount.4Elmore County. Payment Due Dates
For the first installment the math is straightforward. Miss December 20, and interest starts on January 1.
The second installment is where it gets expensive. If you miss the June 20 deadline, interest is not calculated from July 1. It’s calculated all the way back to January 1 of that year.2Ada County Treasurer. Important Tax Dates So the moment you’re late on the second half, you owe roughly six months of back interest on top of the 2% penalty. That retroactive calculation catches a lot of owners off guard, and it’s the single biggest reason to hit the June 20 date.
Unpaid amounts accumulate as a lien against the property until the balance is satisfied. The county doesn’t have to sue you to establish the lien; it exists automatically by operation of law.
If You Stay Delinquent for Three Years
Let delinquent taxes sit for three years and the county can start the process of taking your property through a tax deed. The county tax collector must first send a written notice by certified mail, giving you between two and five months’ warning before the deed issues.8Idaho State Legislature. Idaho Code 63-1005 – Pending Issue of Tax Deed If the certified letter comes back undeliverable, the county publishes notice in a local newspaper for four consecutive weeks.
You can stop the process at any point before the deed issues by paying all delinquent taxes, late charges, interest, and associated costs. Once the tax deed transfers to the county, you lose ownership. Counties do follow through, and the total debt that triggers it can be small compared with the value of the property at stake.