The minimum amount you can top up via Direct Debit is £25*. The maximum amount you can top up via Direct Debit is £20,000*. *Each month, per account. Please bear in mind that ISA and SIPP allowances still apply. Related ArticlesCan I move cash between my accounts?How do I set up a Direct Debit?How can I edit/manage my Direct Debit?How many Direct Debits can I create?Can I set up a Direct Debit from a non-linked bank account?