What is service income and what does it constitute?

Any income earned by providing technical, consulting or other professional services as a part of their trade, profession or business is considered as service income.

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How to declare the personal income earned overseas? I am invited by a government body/Ministry in Singapore to conduct seminars/workshops in Singapore. Is my income taxable? Is personal overseas income taxable? What are the personal taxes that I will have to pay based on my declared salary?