Does the time difference between Lagos and Madrid change during the year?

Yes. Because of daylight saving time the gap moves between −1h and 0.

When is the best time to call Madrid from Lagos?

Between 09:00 and 16:00 in Lagos, which is 10:00 to 17:00 in Madrid.

Lagos is 1h behind Madrid. This gap is not fixed: daylight saving time moves it between −1h and 0 during the year.

Lagos

Nigeria

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Madrid

Spain

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A 9-to-5 day in each city overlaps for 7h. That is 09:00–16:00 in Lagos, which is 10:00–17:00 in Madrid.

City	Time zone	UTC offset
Lagos · Nigeria	Africa/Lagos	UTC+1
Madrid · Spain	Europe/Madrid	UTC+2

What is the time difference between Lagos and Madrid?: Lagos is 1h behind Madrid. This gap is not fixed: daylight saving time moves it between −1h and 0 during the year.
Does the time difference between Lagos and Madrid change during the year?: Yes. Because of daylight saving time the gap moves between −1h and 0.
When is the best time to call Madrid from Lagos?: Between 09:00 and 16:00 in Lagos, which is 10:00 to 17:00 in Madrid.