Amazon.com has made good on its threat to cut ties with Illinois affiliates because of a new law requiring the online store to collect sales taxes.

Amazon notified its Illinois partners Friday that it will stop doing business with them on April 15. It calls the tax law "unconstitutional and counterproductive.

Gov. Pat Quinn signed legislation Thursday that requires online companies to collect sales taxes on Internet purchases if they have any affiliates based in Illinois. Affiliates are businesses that refer customers to Amazon and get paid commissions on purchases.

The sales tax always applied to Internet sales. But individuals — not online businesses — were responsible for paying it. Few people did.