For online businesses as well, selling above a certain amount of revenue or product can trigger what's known as a nexus event in taxation wherein the business becomes liable for collecting sales or use tax. Now online businesses are on the hook for collecting sales tax in every jurisdiction above wildly varying threshold values. Should the business fail to collect the sales tax for selling from Montana to California for instance, then the business will be liable for sales tax not collected for products or services sold to California residents online even though the business might physically reside in Montana.