Economics of collusion question context.
See https://www.justice.gov/opa/pr/two-new-jersey-investors-plead-guilty-their-roles-bid-rigging-schemes-municipal-tax-lien . In some states, when a property holder does not pay their property taxes in a timely way to the local government, the municipality has the right to sell the tax indebtedness at auction. The winner of the auction immediately pays the municipality the full amount of the taxes owed by the property owner. The bidding is for the interest rate that the property holder will owe the auction winner. If after some pre-specified time the property holder does not pay the owed interest to the auction winner then the auction winner has the right to take possession of the property for a price of zero to the current property holder. The auction is an open-outcry descending bid auction in the interest rate. How does this auction design deter collusion by the bidders? Is there a better anti-collusive auction design that typically results in the municipality recovering the full amount it is owed in unpaid taxes?