Cost of ignorance

Now that my report is almost complete, I have to catch up with a lot of things that I could not do this month or two. First I have to make my income tax report to submit to the local tax office which is due this month(Is it? I forget). This is one of the things that I hate. I find myself forget everything that I did last year for filing the tax report.
Technically I am an employer of my wife and actually she takes care of the accounting of my business as a freelance consultant. Why I said "technically" is that paying my wife is rather a tax saving strategy.
When I started working as a freelance consultant I did not know anything about tax. I ended up paying exorbitant amount of tax, so much so that a guy of taxation office staff was kind enough to call me "これで課税させていただきますが、大丈夫でしょうか？ Are you sure with your tax report?"
"I think I am. Is there any mistake?" I said worryingly.
"No, just I felt... that the income deduction seems.... a bit less than....well... average."
"Oh, is it?"
"Ok, ok, it's fine if there's nothing wrong. Thank you."
The line went dead. I thought about it for a while. I realized for the first time that my business expense was so little, since my client pays all the related expenses including my cellphone bill. I bought a computer but it was very cheap. This small sum of expense was all the money that could be deduced from the business income. So the tax was calculated virtually based on the raw figure. Moreover, I did not know that the tax was imposed double; business tax and private income tax. In my case, my business income is my private income. So if the business income, based on which the tax was calculated, increases, my private income also increases.
Maybe I paid the most amount of tax in my life that year (It's not so much by the worldly standard^^). Anyways I knew why the tax office guy said "Thank you" to me. From the next year on, my wife has been my employee. She keeps the accounting book so that we can receive another tax deduction named "blue return? (青色申告). She told me that our health insurance premium, which is determined according to the income, also got significantly lower since then.
You know, ignorance costs a lot.