It’s hard to say for sure how much cash you can deposit in your current account in any one transaction, as each bank may have a different limit but these should be outlined in your T&C’s. However you should note that for out of the ordinary deposits or large transactions above the region of £5,000. The bank may have to ask you some questions to check where the money came from. This may be uncomfortable for you, especially if you’re a long-term customer, but it’s not personal. It’s a legal requirement, due to tighter money laundering laws that were introduced in 2017 and 2020.