LISA and cash ISA

[Hohofortherobbers]

Hi, I have a LISA I have max deposited 4k in and a cash ISA I have so far deposited 10k in with a different bank, I know the total of these ISA deposits must not be more than 20K in 1 year, so I know I can deposit a remaining 6k in the cash ISA this year, however the cash ISA stares I can deposit another 10k in it as it obviously doesn't know I have a LISA elsewhere. Is this just an honesty exercise or would I be penalised for depositing a further 10k....ie 24k total between the cash ISA and LISA?

You cash ISA provider has no way of knowing that you have a LISA elsewhere.
When you pay money into an ISA, you are declaring that you are not exceeding your allowance. If you exceed your allowance, HMRC will eventually contact you... but I don't what happens then. I expect the second payment made over available allowance at that point would be voided, so that money in the cash ISA would be returned and any interest removed. The ISA manager may get fined, so they may pass on costs to you... I don't know.

Keep track yourself of your ISA allowance.

Some examples of Repairs and Voids: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/938842/Worked-ISA-Repair_Void-Examples.pdf

Thank you for the response, not planning on cheating the system but can see how some people could be caught out unintentionally.