Gift Aid can only be claimed on your giving to Stewardship, via give.net or any other means, if you can confirm that your gift comes from your own personal income and you have paid the same amount or more in tax that Stewardship will reclaim.
For example, for Stewardship to reclaim Gift Aid on your gift of £10 you must have paid £2.50 or more in tax during the current tax year. For £1,000,000 you will need to have paid £250,000 in tax.
You can update your Gift Aid status with Stewardship at any time.