From the summary:
"Even when tax haven abusers act perfectly legally, they force other Americans to shoulder the burden in a variety of ways. The taxes they don't pay must be balanced by other Americans paying higher taxes, coping with cuts to public spending priorities, or increasing the federal debt.
Congressional studies conclude tax haven abuse costs the United States approximately $100 billion in tax revenues every year. Multinational corporations account for $60 billion and individuals the rest.
If ordinary tax filers were to pick up the full $100 billion tab in the form of higher taxes, they would need to pay an additional $426 on average. ... "They break out business taxes differently, and estimate that smal businesses, which generally cant't shelter as effectively as big businesses, "would need to pay an average of $2,116 each in additional taxes" to make up for the dollars lost to offshore.