Side income from freelancing, do I need to declare to LHDN?

Declare it, don't chance it. All income earned in Malaysia is taxable, side gigs included, and with e-invoicing rolling out and banks reporting, LHDN can trace things more easily now. Penalties for undeclared income are heavy and not worth the stress. From my experience freelancing on the side, the smart move is to track every ringgit of freelance income and every related expense (design software, laptop, a share of your internet/phone), because you can deduct genuine business costs, lowering your tax. Keep invoices and receipts. You report it during annual e-Filing. Once you set up a simple record habit, it's painless. If you're unsure how to categorise things or want to claim deductions properly, spend a little on an accountant's advice, it usually pays for itself. Stay clean, sleep well.

From my experience, yes, you must declare all your income to LHDN, including freelance/side income, it's taxable regardless of your main job's PCB. 'Keeping quiet' is tax evasion and LHDN has gotten much better at tracking bank inflows and e-invoicing, so it's not worth the risk of penalties later. The good news: as a freelancer you can also claim legitimate business expenses (software, equipment, portion of internet) against that income, reducing the taxable amount. Keep proper records of income and expenses from now. You declare it in your annual e-Filing under the appropriate income section. It's really not scary once you do it. For your specific situation and to maximise deductions correctly, a quick consult with an accountant or LHDN's help channels is worth it. Better to be right than sorry.