Navigating PCB (Potongan Cukai Bulanan): Why Is My Employer Deducting So Much?

Few things confuse fresh graduates more than watching their first payslip and seeing a chunk disappear under "PCB" before they've even touched the money. PCB, Potongan Cukai Bulanan or Monthly Tax Deduction (MTD), is not a separate tax, it is your employer collecting your income tax in instalments throughout the year instead of one lump sum at the end. Here's how the number on your payslip is actually worked out, and why it moves around.

Employers calculate PCB using LHDN's Computerised Calculation Method, built into standard payroll software. In broad terms, the system estimates your total annual income by projecting your current month's salary forward across the rest of the year, applies your statutory EPF and SOCSO/EIS deductions, applies the standard reliefs you're entitled to (including any additional reliefs you've declared to your employer), runs the result through the progressive tax brackets to estimate your annual tax, and then divides the remaining balance across your remaining pay periods.

You don't need to run this calculation yourself, employers are required to use LHDN-approved payroll formulas, but our PCB calculator mode uses the same method so you can sanity-check your payslip.

PCB is not a flat percentage, so it naturally moves when your circumstances change:

• Salary increments or promotions: a higher monthly salary raises your projected annual income, pushing more of it into higher brackets.
• New relief declarations: submitting Form TP1 (to declare additional personal reliefs, such as new insurance premiums or education fees) or TP3 (to declare income and PCB already deducted by a previous employer in the same year) to your HR department changes the calculation from that month onward.
• Marital or family status changes: getting married or having a child, once updated with your employer, reduces future PCB.
• CP38 instructions: if LHDN identifies that you were under-deducted in a prior period, it can issue a CP38 directive requiring your employer to deduct an additional fixed amount for a set number of months.

None of these mean you're being taxed unfairly, the system is just re-projecting your annual liability with better information.

Bonus months look alarming because a large one-off payment can appear to be taxed at a much higher rate. In reality, employers are required to calculate PCB on a bonus separately from your normal monthly PCB: the bonus is treated as additional income for the year, and the extra tax it triggers is deducted in the month it's paid (or spread across the remainder of the year, depending on the method used), rather than being averaged into every future paycheck. It looks painful in that single month, but it is not a higher tax rate on your bonus specifically, it's your existing progressive rate applied properly across your now-higher annual income.

PCB is only ever an estimate. Your actual liability is finalised when you file at e-Filing, where all your reliefs, including ones your employer's payroll system never saw, are applied in full. If the total PCB deducted over the year turns out to be more than your final tax payable, common when you claim reliefs (like lifestyle, medical or SSPN) that weren't declared to your employer via TP1, LHDN refunds the difference automatically after your return is processed, usually credited directly to your bank account.

If PCB fell short, for example because of untaxed side income, you'll owe the balance instead. Either way, filing on time each year, even when PCB has already covered most of your liability, is the only way to settle the exact amount and get any refund owed to you. Use our PCB calculator to check whether your current deduction lines up with what you'd actually owe.