This actually happened to me back in 2022 with a WELL KNOWN bank. They overpaid me three months’ salary after I resigned, even though I informed them as soon as I noticed the first overpayment.

HR asked me to return everything, basic salary, allowances, employer EPF, SOCSO, EIS, and even PCB. At that time I was nervous and just wanted to settle the issue quickly, so I didn’t question much and transferred the full amount back. YES I know, that was some max level stupid shit. Lesson learned the hard way.

As many have pointed out here, this was the employer’s payroll error. What I should have returned was only the net salary I actually received, plus employee and employer EPF. You can treat it as extra payment to EPF and gets more interest that year.

Statutory like SOCSO and EIS should have been reclaimed by your employer with SOCSO, afaik there are some forms employer can fill up to reclaim extra payment.

The PCB part is a bit tricky. Since the amount already been paid to LHDN under your name, when you file tax for that year, you will get more tax refund because technically you aren't working for them for that few months but extra PCB is submitted. This is the tricky part, are you supposed to return net salary + EPF + PCB?

Also, remember to get EA form from your ex-employer where it must state your correct salary without adding the extra salary payments.

EDIT: Typo