There is one entry from 2014 available for Sanders on the Tax History Project website: a Form 1040 (a summary of his federal income tax return) and a one-page Vermont state income tax return. The campaign referred to this entry when we inquired about Sanders’s claim.
Sanders and his wife reported a total income of $205,617 in 2014. The vast majority came from his Senate salary ($156,441 after contributions to savings and health insurance). They paid $27,653 in federal income tax and $7,903 in Vermont in 2014.
The couple received another $46,213 in Social Security benefits, and $39,281 of it was taxable. …
While Sanders rejected [Jake] Tapper’s assertion that the public has no access to all of Sanders’s tax returns, we have no evidence he has released any other federal income tax return than the Form 1040 from 2014. The campaign confirmed to The Washington Post that it did not release other tax returns prior to 2014.
But the campaign did not respond to further questions about this topic, including our questions about his decision to release only a Form 1040 rather than a full tax return — and why Sanders claimed he released other tax returns in the past.