I was carrying £20,000 in GBP on me after a business settlement in China . I decided my best option to carry money home after going on a visit to Vietnam was to carry on my person.
Problem arose when i was stopped by customs security on the way out of Hanoi Airport and asked how much cash i had on me. Thinking i did not have any problem telling them as i had proof with a withdrawal slip of the amount from a Chinese Bank. They produced a list of rules and pointing out my limit was around 5,000 USD ! Showing them the Bank withdrawal slip did not seem to matter to them and read from another list of rules my rights. I was marched into a private room and was told id have a large fine of £4,000 GBP to pay ! Trying to explain that this did not seem fair as i did not know of this part of Vietnamese law ! One of the policemen said he would go easy on me as it was my first offence and said i would have to pay £2,000 GBP. I had no other option as i was told they had the right to take it all off me ! So reluctantly i agreed and had to part with the amount in total of £2,000 GBP.
I was just relieved to get out of there and on my way out the policeman stopped me and produced small form saying if i had filled it in with the amount and gave to customers or aircrew that i would have been able to hold on to all my money ?
They did not even offer me a receipt for the amount i paid ! but as i did not have a leg to stand on and rushing to catch a flight i had to accept !
So be warned ! Fill in that small white form and it seems there is no problem bringing money in and out of Vietnam.