My wife lives and works in South Africa ... I'm currently still based in England... she's asked me for my passport number and has said it's required to complete her online tax return. Is this mandatory as I've only ever been in the country for 2 or 3 weeks at a time so I don't see the relevance. The system doesn't work like that in England so just wanted to know if that's the norm and if there's any alternative for her if I don't provide these details? Any advice is appreciated...thanks for reading. Dan.