ZAKAT AS AN INCOME EXPENSE
Zakat contributions are NOT eligible for 2.5 times tax-deduction.
According to IRAS, Zakat is treated as an expense under section 14 of the Income Tax Act and this is set off against the employment income of that individual. It does not qualify for 2.5 times tax deduction for the applicable period.
For example if an individual pays $200 for Zakat, he or she is only entitled to claim $200 as an expense against his/her employment income.
If you did not opt-in for auto-inclusion when you make your Zakat payment (via any platform), you have to declare Zakat as an expense under employment income as it is not auto-included.