Why is it taking Bernie Sanders so long to release his taxes?

Bernie Sanders has effectively been running for president steadily since, at least, 2015. And over all that time -- which now spans two campaigns for president -- we've seen exactly one year of his tax returns.In the 2016 campaign, Sanders released the two summary pages of his 2014 returns only. He said he would release a more robust tax history if he became the Democratic nominee, which, well, didn't happen. By contrast, Hillary Clinton released eight years of returns -- spanning 2007-2014 -- in August 2015. A year later, in the midst of the general election against Donald Trump,Clinton released her 2015 return.

With Sanders now installed as one of the frontrunners for the 2020 nomination -- and his past resistance to releasing a full picture of his tax history -- his ongoing vague statements about when he might release more of his returns are of note.
"Do you know what April 15th is? It's Tax Day," Sanders told CNN's Ted Barrett earlier this week when asked if there was an issue to releasing his taxes. "So, I think we want to make sure we have all of them together and as I said, they will be released soon."