Last week at the HHS deadline, West Virginia became the seventh state to commit to participating in a state-federal partnership exchange.

FORBES: State-Federal Partnership Health Insurance Exchanges: The Great Unknown

The tax will apply if any party to the transaction is based in a participating member state, regardless of where the transaction takes place - the so-called "residence principle" - and it is this provision that is causing the most controversy.

BBC: Financial transaction tax tabled by European Commission

Freed Maxick, an accounting firm in northern New York state participating in Twitter's test, says the ads it bought on Twitter last fall targeting people looking for U.S. presidential candidates' views on taxes generated 2.1 million clicks on its website.

WSJ: Small Firms Say LinkedIn Works, Twitter Doesn't