In California, certain "necessities" like food are generally not subject to tax. Clothing, on the other hand, is. If you're doing business in New Jersey, however, and you're shipping a pair of designer jeans to the Upper West Side, then there's no tax — in New Jersey, clothing is considered a necessity and therefore is not subject to tax. Keeping track of these rules and exceptions is an ongoing challenge. But wait, there's more. You still have to figure out how much to charge.

    There are hundreds of different sales-tax rates within California alone. First you have state tax. Different counties also have additional rates. And then some cities add a percent or so on top of that! In San Francisco, sales tax is 8.5 percent. Drive across the Golden Gate Bridge to Marin and its 7.25 percent. Across the Bay Bridge in Berkeley it's 8.25 percent. And each state is different.

    If you're doing business internationally, things are further complicated by tariffs, customs fees, and other potential charges. Did you know that in one part of Canada, even tax is taxed? This must be where the people who fled Boston after the Tea Party settled.

    Besides dealing with wildly varying tax rates, you also have a little thing called nexus to contend with. Nexus is a legal term meaning roughly, "where you have a presence doing business." In the United States, you are obligated to collect, report, and pay sales tax in states where you have a nexus. The important thing is that nexus is a legal term, so you should seek the advice of your tax attorney on this issue.

    You should also work with your attorney to develop a tax policy. Of course, you can always do what Apple did when it launched its first online store a few years ago: Just say, "Applicable sales tax will be added to your order" and then let someone else, usually a fulfillment center, figure it out for you using its preexisting taxing systems. But to make sure your customers can pay the full amount of the orders before you process them, you'll need to calculate the tax yourself. There are several packages and services that automate your tax calculations.

    Both of these solutions have advantages and disadvantages, and they're always being improved upon and updated. So you'll need to do a bit of research on which option is the best fit for your e-business. Check out their websites for the features they offer and the e-commerce systems (covered in Lesson 4) they're compatible with. See whether their clients offer products or services similar to yours. You may even want to send an email to people at the companies that use these solutions to inquire about how satisfied they are with the products.