The agreement allows the giant e-commerce company to start collecting sales tax for the state on internet purchases shipped to Idaho.
However, according to the commission, state law bans discussing specific information about an individual taxpayer even though the agreement will impact nearly all Idaho taxpayers.
The commission has also declined to talk about how much sales revenue the state is expected to receive from Amazon and what the state offered Amazon to begin collecting the taxes.
"All we can say is that Amazon has a seller's permit effective April 1, 2017. Any information beyond that is protected by the Idaho taxpayer confidentiality laws," commission spokeswoman Renee Eymann wrote in a statement provided to the office of Gov. C.L. "Butch" Otter.
Amazon confirmed it had brokered a deal with the state on March 16. Otter's office then praised the deal.
"We consider this a matter of fairness," Mark Warbis, Otter's spokesman, said in a prepared statement.
Emails obtained by The Associated Press under a public records request show the commission did talk media logistics with Otter's office before the deal was made public.
Amazon collects sales taxes in all but a handful of states.
Idaho shoppers have always owed state sales taxes on purchases they made online, but the rule has been widely ignored because it requires consumers to self-report and pay the taxes on their own.
Idaho and other states have spent years examining ways to capture the lost tax dollars, but their options are limited when the retailers are not based in the state.
A 1992 Supreme Court decision said retailers must have a physical presence in a state before officials can make them collect sales tax.
It's unclear if the Amazon deal in Idaho will prompt a larger effort to collect sales taxes from all online retailers.
Lawmakers in Arkansas and Utah failed to finalize a tax collection proposal during their legislative sessions this year despite securing separate deals with Amazon.
--The Associated Press