That calculation is a lot higher than the $1.2 billion in taxes that Pfizer (PFE) estimates it will save next year as a result of the $160 billion deal with Allergan (AGN), expected to close later this year.

But while ATF, a group that supports increasing taxes on the wealthy and big businesses, accuses Pfizer of using accounting tricks and offshore havens to evade U.S. taxes, it’s using its own sort of fuzzy math—making it look like Pfizer is “dodging” taxes it probably would never even owe in the first place.

Companies owe U.S. taxes on profits they bring home to this country. But for multinational companies with extensive foreign operations like Pfizer, it isn’t always necessary to repatriate overseas earnings. And yet to get to $35 billion, ATF assumed that Pfizer would eventually bring all of its profits earned overseas back to the U.S.—an extremely unlikely scenario.

In its calculation, ATF started with an estimate that Pfizer owes about $14 billion in U.S. taxes on $74 billion in earnings from its international subsidiaries. But those earnings are “intended to be indefinitely reinvested overseas,” according to Pfizer’s latest annual report from 2014, in which the company also says it can’t even determine the U.S. taxes it would owe on the sum because such a “hypothetical” calculation “is not practicable.”

To the $14 billion, ATF added Pfizer’s $21 billion in deferred taxes on other foreign earnings—deferred meaning Pfizer would not actually have to pay that amount until it decided to bring those earnings to the U.S. But while Pfizer accounted for the deferred tax liability in its 2014 report because it didn’t expect to keep the profits overseas forever, ATF believes that once it moves to Ireland with Allergan, Pfizer may defer paying those taxes in perpetuity.

Still, even before the Allergan deal, Pfizer had for years deferred paying taxes on its overseas earnings—which make up the bulk of its overall tax liability. So there was no indication that Pfizer was ever planning to pay these taxes at all. In the past, Pfizer has chosen to repatriate profits under special circumstances, such as to help it pay for an acquisition, or on a federal tax holiday.

Pfizer does expect to lower its tax rate through the Allergan deal from about 25% now to 17% in the coming years. But ATF’s argument, which multiple accountants told Bloomberg was “misleading,” seems to blame Pfizer for saving money that the U.S. government isn’t entitled to collect.

A spokesperson for Pfizer declined to comment on the report, but said the Allergan deal was not intended to move jobs out of the U.S., where Pfizer does the majority of its research.