Very laudable attitude I'm sure but ignoring the tax office isn't the same as not paying a parking ticket. You may get away with it for several years but a knock on the door entails paying back taxes and a large fine as well as criminal proceedings. I don't know how it is here but in Europe tax evasion is a criminal offence, if that is also the case here then your visa extension could also be revoked, is it worth the risk?
I have several pensions but it's all quite straight forward, I have calculated my deductions and worked out my own tax bill....just over 20k. In most cases you won't need a tax consultant and I have heard that the tax office staff are very helpful for a little tea money. I don't like the idea of paying tax, who does, but I will wait until the last day and then present myself at the tax office with my calculations, I'm too much of a coward to break a lance on the doors of the tax office.