Secondly under the Gift Aid scheme whenever a UK tax payer (it's simply a qualification to be registered as a tax payer  - it's not necessary to be paying income tax) makes a registered donation, the relevant Charity can claim from the Inland Revenue 27% of the specific donation, on the basis that in theory the donor has already paid 22% income tax on the amount given to the Charity.

What is a "registered donation?"  A registered donation to what?  A specific charity?

I take this to mean that there isn't really a payment by the government, just a return of the taxed portion of the after-tax donation that someone might make.

If this means what I think it does, then it really isn't that different than what happens in the US., but in the US none of the money would go through the government.  So, if a taxpayer donates money to a charity, they deduct that from their income before they pay taxes on the rest.  That's what is called a "tax deductible donation."  In most cases you can deduct for both Federal and State income tax purposes.

S