They ask for details of your bank accounts. You only have to give them whatever you decide to write down. There isn't someone ringing round all the banks that exist and asking whether you have an account and even if there is the bank will say "Sorry, can't tell you that mate, fuck off now".
True. And of course you can lie. BUT you have to also make a declaration that you personally have no other monies than those you've declared on the form. I highly doubt they don't have the power to get the info from your bank if they formally investigate you.
If you are investigated for any reason, obv, this will be deemed as fraudulent.
Also, they ask to see statements of your current accounts for the previous 6 months etc as well, and keep those on file.
They knock back tons of applications for benefits (council/house/JSA) for all sorts of stupid reasons.
When I made my claim after not claiming for two years they denied all my applications because of a £500 LOAN which had been going into my account each month, which they counted as an INCOME. Fucking lunacy. Took months to sort out, and especially annoying because I was actually entitled to money for the previous 2 years that I didn't claim, so had been claiming nothing at all even tho I was entitled.
I would advise anyone to be upfront about their accounts, because if there's just a tiny reason or connection that they can refuse your claim, they will and do investigate your accounts
[edit]
Also, say knock went and paid off a bunch of his credit cards or summat, which brought his savings down to below 6k, so he could claim, they often take that as willing making yourself poor (can't remember NB's terminology he just used), and will refuse an application because you've done it on purpose so to speak.