here and here that Lembaga Hasil Dalam Negeri (LHDN) @ Inland Revenue Board (IRB) is barring tax evaders from leaving the country at Immigration counter or airport auto-gate. It looks like now, the IRB has engaged the support from Immigration Department to enforce travel 'blacklist' for those who didn't settle their tax accordingly. I can't imagine the trouble of being stopped at immigration counter or auto-gate when we are ready to board the flight somewhere for a nice vacation which we had been waiting for so long. Can't imagine had to tear off the boarding pass :(
So, if you suspect you are one of the the tax evaders, it's better to check whether you're in the LHDN @ IRB Travel Blacklist or not, before you proceed with your travel arrangement. You can check for LHDN @ IRB Travel blacklist here. Just key-in your 12 digits Malaysian Identity Card (IC) Number will do. From the reply, you will know whether you're valid to travel or had been restricted to do so. If you're restricted to do so, there're possibilities that you're blacklisted and you must contact Immigration Department for further information.