Does the time difference between New York and Toronto change during the year?

No. Both cities keep the same local time all year.

When is the best time to call Toronto from New York?

Between 09:00 and 17:00 in New York, which is 09:00 to 17:00 in Toronto.

New York and Toronto are on the same local time. This gap is the same all year — neither city shifts its clocks relative to the other.

New York

United States

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Toronto

Canada

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A 9-to-5 day in each city overlaps for 8h. That is 09:00–17:00 in New York, which is 09:00–17:00 in Toronto.

City	Time zone	UTC offset
New York · United States	America/New_York	UTC−4
Toronto · Canada	America/Toronto	UTC−4

What is the time difference between New York and Toronto?: New York and Toronto are on the same local time. This gap is the same all year — neither city shifts its clocks relative to the other.
Does the time difference between New York and Toronto change during the year?: No. Both cities keep the same local time all year.
When is the best time to call Toronto from New York?: Between 09:00 and 17:00 in New York, which is 09:00 to 17:00 in Toronto.