Income tax for secondary income and personal loan
In 2010, I granted the owner of a horse pension stable a private loan of approximately 17,000 euros for the construction of a stable building where my horses were then housed. In 2010, around 1,000 euros of interest accrued (for the following years, we agreed on an interest-free loan).
Additionally, I myself helped with the construction of this stable (without being officially employed by the stable owner), for which we had agreed on approximately 3,000 euros in wages. I did this in addition to my regular job (employee) and did not register a business - it never occurred to me that there could be tax issues; it was simply meant as assistance.
The repayment of the loan has been ongoing since September 2010 and will continue for another 2-3 years. I have not yet received the interest (1,000 euros) or the wages (3,000 euros), but will receive them over the next few years.
Therefore, my questions are:
1) In which year should the interest (1,000 euros) and wages (3,000 euros) be taxed: in 2010, because I received them formally, or in the year in which I actually receive the money? If I had to pay taxes on them in 2010, that would mean paying taxes on money I have not yet received.
2) How do I report the wages on my tax return? Since I did not register a business and typically only have income from "non-self-employed work," I am unsure which form and format to report this on.
3) I have already filed my 2010 tax return without considering that taxes may be due on these earnings. How can I rectify this and report the additional income?