If a foreigner is present in Vietnam for fewer than 183 days in the first year of arrival in Vietnam, he/she shall make PIT accounting at the time of full 365 days. From the second year, the foreigner shall make PIT accounting at the end of the calendar year (point e.2 Clause 2 Article 26 of Circular No. 111/2013/TT-BTC
With regard to a non-resident (he/she is present in Vietnam for fewer than 183 days in a calendar year or does not has a contract of leasing house with a term of at least 6 months), he/she shall be exempt from making PIT accounting. However, his/her income shall be deducted 20% PIT.