up vote 19 down vote. There is no limit to the amount of cash you can carry, however if you are carrying more than $10,000 USD (or equivalent in foreign currency) then you must declare it (full details on how to do that at the URL above).However bringing cash is very rarely the best strategy for foreign exchange.hen you are departing from the UK and travelling to a non-EU country, you have to declare if you have €10000 or equivalent at UK customs (around $13000). Then on entry to the USA you will have to declare if you are carrying $10000 or more.