29/05/2026
I always thought stained notes were just someone smearing ink on the notes or some printing defect. Turns out it is anti-theft technology built right into the ATM.
BNM uses ink-stained technology (https://bnm.gov.my/documents/20124/749650/Ink-Stain_Pilot_Program_FAQs.pdf). Dye packs are placed inside the cash bundles in ATMs and cash-in-transit bags.
If someone tampers with the machine or the bag, the pack activates and releases indelible ink that stains every note in the bundle.
BNM formalised the guideline in August 2020, asking financial institutions and cash-in-transit companies to deploy as a deterrent against ATM robberies. The ink is reportedly non-toxic to humans.
Here is the clever part.
Cash deposit machines are programmed to detect and reject stained notes. Bank branches are instructed not to accept them either. Anyone trying to deposit one may be tracked down for questioning.
The note is functionally worthless the moment it is stained. You cannot spend it, deposit it, or exchange it without potentially being investigated.
The deeper logic is elegant. The thief can still break the ATM open. But the cash inside becomes useless the second they touch it.
The robbery is no longer worth attempting.
Time to check your wallet if you have any such bank notes.
via X/
