Start by comparing the AER, which shows the account’s yearly interest rate, and check whether it is fixed or variable. Look at access rules, withdrawal limits, minimum deposits, introductory bonuses and when interest is paid, as the highest rate may not offer the flexibility you need. Consider whether a cash ISA could shelter interest from tax, depending on your circumstances, and check that deposits are protected by the FSCS where applicable. Rates and terms can change, so confirm the current details directly with the FCA-authorised provider before applying.