If the good cause you are supporting is eligible for Gift Aid there will be an option for you to select it in your account - You need to click the heading and fill out your details then click 'Save'.
Please check this every time you change your cause as a Gift Aid declaration is only valid for each individual good cause.
If you can't see a title that says Gift Aid it means your good cause haven't let us know they can make a claim. If you think this is wrong please let us know.