International mail fail
 

Howdy people!

I sent a package earlier today from Japan to UK with EMS, and filled out the forms in a hurry (stupid, I know) since I had a rather busy morning. Looking at the carbon copies of the customs forms, I realise that I forgot to mention one of the items in the package.

Do customs (either Japan or UK) actually check the contents of every package? Is it likely the package will be detained / returned to sender at all? Basically... what's the worst case scenario, if anybody knows?

Thankfully the contents aren't that expensive, so I'm not too worried, but would like an idea of the package's potential fate none-the-less.

Cheers folks

Depends what the item was you didn't declare. If it's a restricted or sensitive good (food things, for example), then it might be opened and if it's something you ~really~ should have declared then it might well be detained. Failing that you might then be subject to extra customs charges.
I did a similar thing with a very large box where I forgot the list of items in it and had to fill the form from memory. Naturally I forgot a few things, but the box arrived at the expected time and didn't appear to have been opened by customs.