The annual ISA allowance may vary each tax year. The ISA allowance for 2017-18 tax year is £20,000. When you are funding your Ablrate IFISA we have an automated check on what allowance you are allowed to invest so that you don’t over-fund accidentally.
You may consult the government website for the current ISA allowance.
PLEASE REMEMBER, REGARDLESS OF THE TAX BENEFITS, CAPITAL IS AT RISK
Whether investments are held within a IFISA or in a general account, they are not covered by the FSCS; the government backed deposit insurance scheme that protects bank deposits including Cash ISAs.