зависит от того что (где) вы будете покупать.
Online магазины имеют привязку к штату, и если вы зарегистрируетесь в "его" штате, то они снимут налог несмотря на онлайновость.
Если электронику - то достаточно вкусный NewEgg.com расположен в Кали, так что стоит выбрать Масс.

Ну так и вы не в Кали живете.

физическое присутствие.
Некоторые онлайн-ретеллеры вообще выносят варехаусы в отдельное юридическое лицо, чтобы их не заставляли брать налог.

http://www.newegg.com/HelpInfo/FAQDetail.aspx?Module=2

Does Newegg charge sales tax?

Newegg charges the appropriate state and/or local sales tax for any order shipping to California, New Jersey, and Tennessee. Sales tax for cell phone orders shipping to California and Tennessee are calculated before any instant savings are applied.

Tennessee and New Jersey residents are charged according to their state and/or local tax rate. Please note that the sales tax for New Jersey and Tennessee orders is calculated based upon the total price of the order, including shipping and handling. The tax imposed by these states on shipping and handling is part of the state sales tax, not a separate tax.

California residents are charged sales tax as follows:
Los Angeles County residents: 9.75%
City of Pico Rivera residents: 10.75%
California residents outside of Los Angeles County: 8.25%

For further information concerning California sales tax, please refer to www.boe.ca.gov.
For further information concerning New Jersey sales tax, please refer to www.state.nj.us/treasury/taxation/.
For further information concerning Tennessee sales tax, please refer to www.state.tn.us/revenue/.

Although Newegg only charges sales tax on sales shipped to the states mentioned above, please note that your state of residence may require you to pay sales or use tax and file a sales or use tax return for certain purchases made from Newegg. Please consult your city, county and state tax rates to determine your applicable sales or use tax.

не совсем так. В кои веки Нарото не соврало.

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Although Newegg only charges sales tax on sales shipped to the states mentioned above, please note that your state of residence may require you to pay sales or use tax and file a sales or use tax return for certain purchases made from Newegg. Please consult your city, county and state tax rates to determine your applicable sales or use tax.
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Вот тут можете посмотреть, обязаны ли вы в Tax Return указывать онлайновые покупки :

http://www.ecommerce-blog.org/archives/the-myth-of-tax-free-internet-sales/

Обязаны везде, кроме Аляски, Делавара, Нью Хэмпшера и Орегона.

онлайновые покупки в этом плане не отличаются.
Взять Масс :

http://www.mass.gov/?pageID=dorterminal&L=6&L0=Home&L1=Individuals and Families&L2=Personal Income Tax&L3=Forms & Publications&L4=Publications&L5=Publications Index&sid=Ador&b=terminalcontent&f=dor_publ_sales_use&csid=Ador

What is the use tax?

The Massachusetts use tax is 6.25 percent of the sales price or rental charge on tangible personal property 1 (including phone and mail order items or items purchased over the Internet) or certain telecommunications services 2 on which no sales tax, or a sales tax rate less than the 6.25 percent Massachusetts rate, was paid and which is to be used, stored or consumed in the Commonwealth. The use tax, unlike the sales tax, generally is paid directly to the Commonwealth by the purchaser.

То есть, если вы заплатили в соседнем штате меньше 6.25, и используете, храните или потребляете товар на территории Масса, то вы обязаны заплатить Use Tax подавая декларацию. А покупали вы диваны онлайн, или оффлайн - налоговую не волнует.

Понятно, что 99% покупок проходят незамеченными налоговой, и 98% их не декларируют, но законолательно это именно так.