Tax deductions for sole trader

[ecmandria_t]

I have been doing some research and have found how the tax department look at it if you use a business facility for private use (like a house or a car), but what happens the other way round?

What could you deduct for using a room in a house you own as an office for your business? Or for using a privately owned car for a business trip? Or using a privately contracted internet connection for business?

Any tips would be welcome. And if you have links to documents, even better!