Time in Argentina

Argentina is located at a longitude that would naturally put it in the UTC−04:00 or UTC−05:00 time zone; however, it actually uses the UTC−03:00 time zone. Argentina determines whether to change clocks in observation of daylight saving time on a year-by-year basis, and individual provinces may opt out of the federal decision. At present, Argentina does not change clocks.

The Argentine Hydrographic Service maintains the official national time.

History
The first official standardization of time in Argentina took place on 31 October 1894, with establishment of UTC−04:00 as the nation's standard time. From 1920 to 1969, the official time switched biannually between UTC−04:00 as standard time in winter and UTC−03:00 as daylight saving time in summer. From 1974 to 1993, clocks advanced again, such that the official time switched biannually between UTC−03:00 as winter DST and UTC−02:00 as summer double DST. In 1993, the national time was fixed at UTC−03:00, called Argentina Time (ART; hora oficial argentina, HOA). In 2007 and 2008, biannual switching between UTC–3:00 (winter DST) and UTC–2:00 (summer DDST) resumed; in 2009, this was replaced again with year-round UTC–3:00 (permanent DST).

IANA time zone database
In the file zone.tab of the IANA time zone database Argentina has the following zones:
 * 1) America/Argentina/Buenos_Aires – Buenos Aires (BA, CF)
 * 2) America/Argentina/Cordoba – most locations (CD, CC, CR, ER, FO, MN, SF)
 * 3) America/Argentina/Salta (SA, LP, NQ, RN)
 * 4) America/Argentina/Jujuy – Jujuy (JY)
 * 5) America/Argentina/Tucuman – Tucuman (TM)
 * 6) America/Argentina/Catamarca – Catamarca (CT), Chubut (CH)
 * 7) America/Argentina/La Rioja – La Rioja (LR)
 * 8) America/Argentina/San Juan – San Juan (SJ)
 * 9) America/Argentina/Mendoza – Mendoza (MZ)
 * 10) America/Argentina/San Luis – San Luis (SL)
 * 11) America/Argentina/Rio Gallegos – Santa Cruz (SC)
 * 12) America/Argentina/Ushuaia – Tierra del Fuego (TF)
 * 13) America/Argentina/Santiago_del_Estero (SE)