Does the time difference between Manila and São Paulo change during the year?

No. The gap stays at 11h all year.

When is the best time to call São Paulo from Manila?

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

Manila is 11h ahead of São Paulo. This gap is the same all year — neither city shifts its clocks relative to the other.

Manila

Philippines

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São Paulo

Brazil

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A 9-to-5 working day in Manila does not overlap one in São Paulo at all — somebody has to take the call outside office hours.

City	Time zone	UTC offset
Manila · Philippines	Asia/Manila	UTC+8
São Paulo · Brazil	America/Sao_Paulo	UTC−3

What is the time difference between Manila and São Paulo?: Manila is 11h ahead of São Paulo. This gap is the same all year — neither city shifts its clocks relative to the other.
Does the time difference between Manila and São Paulo change during the year?: No. The gap stays at 11h all year.
When is the best time to call São Paulo from Manila?: There is no overlap between standard working days, so one side has to call early or late.