ISA from previous tax year - trading allowed?

[fab1]

Hi,

 

I have an existing ISA account with IG that's been funded in previous tax years. If I open and start funding a new ISA account this tax year with another provider, do the ISA rules still permit me to trade within my existing IG account?

 

I understand only one ISA account can be funded per tax year, so my question is about trading only within existing accounts that aren't being funded anymore.

 

Thanks for your help.