Stamp duty is not payable when gifting a property when there is no mortgage on it.
Stamp duty is payable by the receiver of the gift when the property has a mortgage attached to it.
Even if you are married or in a civil partnership, if there is a mortgage when you gift property from one spouse/civil partner to the other or the property is gifted from single to joint names, stamp duty may be payable.
If it is your main residence, normal stamp duty rates apply.
If it is an additional property/2nd property/buy to let property, normal stamp duty rates apply plus the 'additional property' 3% stamp duty land tax rate is added to all rates.