The Centre for Effective Altruism UK (the legal entity behind EA Funds’ UK operations) is registered in the Netherlands as a tax-deductible charity.
When you get to the payment page you can select which country you’d like to donate in. To donate in a way that’s tax-deductible in the Netherlands, select ‘UK/NL’ as your country, and then optionally select EUR as your currency code. You can donate via credit card or SEPA transfer.
ETA: I’ve updated the relevant FAQ entry to make this clearer.