How to claim Tax refund for excess tax deducted by employer?

No you don't mix tax years 2017 and 2018.

Your final tax bill is usually decided when the company submits the Leavers Form, but they also usually retain the last months salary in case there is a tax shortfall.

Any 2018 tax would be sorted out through the Leavers procedure (not through an annual tax return for 2018). But if in doubt, you could always file for a second opinion in 2019

I am surprised you did not complete the BE 2017 as part of the Leavers process.  You should do that as normal and see if LHDN pick up the issue.

You can process a Request for a Refund if you think LHDN has received too much tax from you. This would be done directly with the usual tax office that handled your file.

I assume you have a copy of the Leavers form (which I think you have to sign) so you can see what happened.

Dear Gravitas,
Thanks for prompt response.
Yes, I signed the LEAVER form & completed the BE process for year 2017 & 2018 , as asked by LHDN while I personally submitted my application for tax clearance. The process completed with LHDN giving me Tax Clearance Letter (addressed to my company with copy to me), that mentioned the final tax liability. However, my employer had deducted excess tax and paid to LHDN.
Will the excess tax deposited by my company be refunded by LHDN to my bank account without any further action from my side (since I do not need to file tax return as I understand from your above response) ?
Thanks again,
RK

Mentioned Tax Refund request earlier - here are some details, including an email address, which may be helpful starting point

It is referring to Tax Filing but there is at least contact information.

Tax Refund

Tax Refund will be credited into the account automatically to the taxpayer within 30 working days after the submission of Income Tax Return Forms (ITRF). However, if you do not receive your refund you can forward your application to the Collections Unit of the branch where your file is located or complete and submit via our Feedback Form http://maklumbalas.hasil.gov.my// or by calling Hasil Care Line at toll free number 1-800-88-5436 (LHDN).

Source: http://www.hasil.gov.my/bt_goindex.php? … p;bt_lgv=2

There is also a customer feedback form at this location of their websitee

http://www.hasil.gov.my/bt_goindex.php? … ;bt_sequ=1

Yes, you may claim the overpaid amount from LHDN. You have to attend personally to LHDN Head Office and bring along with your payslip shown the deduction by your employer. Don't forget to bring along the Clearance letter as they need the reference file number to search out your personal file. They will have a close discussion with you in 1 room. You may solve the issue immediately, but for them to prepare and issue out the cheque with the overpaid amount may take 2 weeks to 3 weeks working day.
The suggestion you to go early in the morning.
If the time frame does not suit to your situation, try to find a solution on how to receive/collect/clear your cheque (You may need someone favour to do it for you). Ask the LHDN Officer if in case you need someone to receive the cheque on your behalf, what would their advise.

Hoping this may help.

Dear Gravitas,
Thanks a lot for prompt response again and very helpful links.
Truly appreciate it.
Regards,
RK