If you're not getting a competitive rate on your ISA, or your fixed rate is about to end, then you can transfer your ISA savings and investments into a different ISA. This will not count towards your annual ISA allowance, so won't affect how much you can pay in to an ISA for that tax year.
For cash ISAs, you can transfer the money into another cash ISA, or, if you are looking for potentially higher gains, you can transfer the money into a stocks and shares ISA. The current year's allowance can only be transferred whole, and cannot be split into two.
The ISA transfer rules also state that while you can transfer from cash to shares, you cannot transfer money from a stocks and shares ISA into a cash ISA. It's a one way street. So, if you have already paid in your total ISA allowance for the year, and you do not want all your tax-free savings in stocks and shares, then you might want to consider leaving some savings in a cash ISA.
If you are transferring a current year subscription from a cash ISA to a stocks and shares ISA it is treated as if that amount was always invested as a stocks and shares ISA. This means, as long as you are within the current annual allowance, you can open a new cash ISA during the same tax year.
By keeping some savings in a cash ISA and some in a stocks and shares ISA it can help diversify your investments, with some savings in safer cash deposits and some invested for higher potential returns, but greater risk in stocks and shares.
While most ISA providers allow transfers in, some don't. And, under current ISA transfer rules, you might be charged a penalty by your current provider – this is becoming less common, but check with your provider, as the fee could potentially offset the benefit of transferring to an ISA with a better rate.
See the tables below for more ISA transfer ideas, including a range of stocks and shares ISAs: