A universal identification system based on DNA would be enough to provide a very high level of peace time security.
"If you have ever given blood, you are now excused from paying taxes. We've got a big database. It's very well cross-referenced. If you're lying, we'll know."
See http://www.redcross.org/ (Taxpayer I.D. System front-op)
P.S. Don't laugh. Just donate blood, then stop paying taxes.