I'd laugh at that, but I'm a little too cynical to think that the NSA isn't entirely likely to get the IRS to throw a "parallel reconstructed" Capone style charge at him just to avoid having to go to court and admit any of their myriad of best-practice security failings…

As a US citizen the answer is always 'yes' even if you lived on the moon.

Since he can never return to the US anyway, there are charges against him, it is kind of pointless.

But on the off chance there's some loophole in Russian law (or the laws of some country he passes through in the future) that makes extradition to the US for tax evasion particularly easy, filing and paying his taxes may be worth the cost and effort.

Or if by some long shot some future president pardons him, he'll be glad he paid his taxes.

I'm not sure if Russia has a "double taxation" agreement with the US and a quick google doesn't immediately prsent an answer. If so, expats who pay taxes in Russia won't have to pay those same taxes in the US. As long as Snowden files his taxes, he won't be under a tax obligation or legal liability.

I am not a lawyer!

There is a US-Russia double taxation treaty.[0]

He'll be eligible for the foreign earned income exclusion by filing time. That protects US persons from double taxation up to about $100k of earned income, even without a tax treaty.

And he needs to remember to file his FBARs, too.

[0]http://www.irs.gov/Businesses/International-Businesses/Russi...

Maybe he's owed a return this year?

I'd assume he would. First of all it could be a risk not to and second, why wouldn't he?