Does the time difference between Buenos Aires and New Delhi change during the year?

No. The gap stays at 8h 30m all year.

When is the best time to call New Delhi from Buenos Aires?

There is no overlap between standard working days, so one side has to call early or late.

Buenos Aires is 8h 30m behind New Delhi. This gap is the same all year — neither city shifts its clocks relative to the other.

Buenos Aires

Argentina

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New Delhi

India

--:--:--

A 9-to-5 working day in Buenos Aires does not overlap one in New Delhi at all — somebody has to take the call outside office hours.

City	Time zone	UTC offset
Buenos Aires · Argentina	America/Argentina/Buenos_Aires	UTC−3
New Delhi · India	Asia/Kolkata	UTC+5:30

What is the time difference between Buenos Aires and New Delhi?: Buenos Aires is 8h 30m behind New Delhi. This gap is the same all year — neither city shifts its clocks relative to the other.
Does the time difference between Buenos Aires and New Delhi change during the year?: No. The gap stays at 8h 30m all year.
When is the best time to call New Delhi from Buenos Aires?: There is no overlap between standard working days, so one side has to call early or late.