I've never used that calc but I'm assuming you put your wife's €1 in as PAYE income. The calc is giving the PAYE credit of €1270 (less 20% tax on €1) = €1,269.80, which is incorrect
The PAYE tax credit should be restricted to 20c, so there is no difference
OK - so the individualisation issue relating to the taxation of married couples with [broken link removed] is probably not the explanation? I've emailed this link to Karl Grabe for him to have a look at.
no - my understanding is that your hubbie (or wife as the case might be!) has to earn at least 25,000 in order to get the benefit of tax individualisation. Other wise the higher earner pays the higher rate on any income he (or she) earns over 43k.