I have a UK Mortgage (let's say outstanding mortgage is £200,000) and an 'offset' savings account of the same amount (also £200,000). As it is an offset account, I don't earn any interest on my savings, but I pay less interest on my mortgage. Question: Do I have to declare the £200,000 of savings on my Dutch tax return? If so, will I get taxed on it at 1.2%, even though it is just offsetting my mortgage? I will be fully resident in the Netherlands as of the next tax year, with no longer any 30% ruling.