1948 to be exact. He got the basic fact wrong.
(From 208) In North Korea, April 1st is commemorated as Tax Abolition Day. Ever since the law, On Completely Abolishing Taxes, was ratified through the Supreme People's Assembly on March 21, 1974, North Korea has claimed both within and without to be the only country in the world that does not collect taxes.
http://www.dailynk.com/english/read.php?cataId=nk02900&num=6203
Do you know how it is today?