You cannot fund more than one Cash ISA in the same tax year. If you have already opened a Cash ISA in this tax year with another provider, then you cannot open and fund a new Cash ISA with Republic Trust Bank unless:
However, please be aware you can hold a Stocks and Shares ISA as well as a Cash ISA in the same tax year and split your total annual ISA allowance across both up to a combined limit of $20,000 in the 2020/2021 tax year. This means if you currently hold a stocks and shares ISA in this tax year, but do not hold a Cash ISA, you can open and fund a Republic Trust Bank Cash ISA.