Second-Installment Cook County property taxes are due Dec. 15, for nearly 1.8 million Cook County properties. That means property owners have less than two weeks to pay in full to avoid late-payment interest charges. The bills were mailed Nov. 14. Property owners unable to pay their tax bills in full by Dec. 15, should look at the free online financial planning tool that helps you make smaller, more manageable payments over time. It’s called the Payment Plan Calculator and it’s available Dec. 16 — one day after the due date — at cookcountytreasurer.com. The calculator lets you:

• Set up a schedule to pay off a tax bill in smaller increments instead of all at once.

• Choose between making payments once or twice a month.

• Create a personalized plan for catching up on delinquent taxes if you owe more than $100.

And you don’t have to wait to sign up. You can register now at cookcountytreasurer.com. Then click on the purple box. Enter your PIN or your property address and hit continue.  Then scroll down until you see the Payment Plan Calculator next to the Pay Now button.  Click it and a page will appear asking you to type your name and email address.  After you enter your information, you’ll receive an emailed reminder from the Cook County Treasurer’s Office to set up your payment plan when the calculator goes live after the due date has passed. During those 13 months interest will be charged at 9% a year, or 0.75% a month.