I don't think you can 'hide' it @beautifulsun
I know someone right now who is on contributory based ESA, (around £140 a week,) and a high rate of PIP - and her DH earns a decent amount. She discovered that once your savings go over £6,000, they can start taking deductions from your ESA.
Many people think it's £16,000 savings before any benefits (eg ESA) are affected. It's not true. They will start taking a certain % away when your savings hit £6,000. For each £1,000 you have saved, they deduct more and more, til your savings hit £16,000, and they stop it altogether. Then good luck getting back on it!
Anyway, this woman I know hit nearly £6,000 in savings, and was so worried about her ESA being stopped, that she has been squirrelling money away at home, so they can't see it. £5300 hidden away in £20 and £10 notes under her bed!
Her defence is that she doesn't want the ESA stopping, as the surplus/savings she and her DH have could go really quickly if her DH lost his job, or he was on the sick for several months, or they had a big car expense, or a large vet bill. And if it's stopped, she will never get back on it. So she has over £5K hidden at home, as well as nearly £6K in savings in the bank! They also have no mortgage, and a 2021 registered Astra (paid for!) And they go on holiday abroad every year.
Whilst I see her point, it does not sit well with me that she has a cheeky nest egg of over ELEVEN THOUSAND POUNDS, (in the bank - and under the bed!) and is claiming the full amount of ESA!
/