Trying not to be technical but hopefully I may answer a few of your doubts.
If of interest, you may want to read up the Malaysian Income Tax Act @
MITA or various public rulings (you may view it as tax guides) published by the LHDN.
Refer below for some comments on your initial post:-
a. Profit before tax - The tax computation for most business should start off with profit before tax (which may or may not required to be audited depending on your circumstances), unless we are talking about specialised industries such as life insurance, banking etc.
Does it make sense to you if we would to use profit after tax (PAT)? Since the tax expense booked would have taken corporate tax (sort of like double counting / the tax expense might be a provisional amount too?) & withholding taxes (might not be applicable to most cases unless have foreign income subjected to tax at the source country) into account.
b. Non-business income - Malaysian Income Tax Act (MITA) taxes income based on "classes of income", i.e. different sources (rental, business, dividends etc.) under different section of the Act.
Non-business income will still be taxed albeit at the lower section / towards the bottom of the tax computation (i.e. for the presentation of different income source) after adjusted income from the said business source.
c) Non-deductible expenses - Essentially these are expenses that are not incurred for the production of income or specifically disallowed under the MITA - i.e. "incurred test" has to be satisfied. e.g.of non-deductible expenses includes entertainment expenses (might be 100%, 50% or non-deductible depending who's being entertained), accounting depreciation (instead tax depreciation aka capital allowance would be allowed for deduction), personal expenses (100% non-deductible), provisions (i.e. no constructive obligation by the company to incur the expense) booked in company's account etc.
d) Special deduction - As mentioned by forummer above, these might be incentives (not to be mistaken with tax incentives in the form of tax holiday) given by the gov for certain governmental initiatives / special deduction for expenses otherwise non-deductible due to the "incurred test" (i.e. audit fees, secreterial fees, tax compliance fees etc)
e) Double deduction - These might be incentives given by the gov for certain governmental initiatives.
Simple illustration, apologies for the spacing & tabbing PBT per P&L RM100
(-) Non-taxable income (might be taxed after business adjusted income / or not at all if say capital in nature) -RM10 from dividend income recognised in company's P&L
(+) Non-allowable expenses (to increase the taxable income as these expenses are non-allowable expenses for tax purpose) -RM25 from RM10 accounting depreciation, RM10 personal expenses and RM5 audit expenses recognised as company's expenses in the P&L
(-) Special deduction -RM5 (note that audit expenses is not incurred for the production of income, but it is specifically allowed, for presentation purpose to be shown under special deduction)
(-) Double deduction -RM0
Adjusted income (from business source) RM115 (RM90-RM10+RM25-RM5-RM0)
(+) Balancing charge / Balancing allowance (tax gain or loss on disposal)
(-) Capital allowance -RM12 (tax depreciation)
Statutory income (from business source) RM103 (RM115 above - RM12)Income from non business source
(+)Dividend income RM10
Aggregate income RM113 (RM103+RM10)(-)Business losses (if any from prior years, max capped at aggregate income, cannot be lower) RM0
(-)Approved donation (with suppporting) RM2
Chargeable income RM111 (RM113 - RM2)Corporate tax at: Chargeable income * prevailing corporate tax rate (Different for SME and non-SME you may read that up as well)
(-)Tax credits to offset corporate tax (might not be applicable to all, such as foreign tax credits, R&D credits etc.)
Tax payable for the year = Corporate tax calculated less tax credits
This post has been edited by CrayonsEater: Mar 20 2019, 10:06 PM