I just started investing in 2021 and upon reading how to calculate the tax I owe for my accumulating ETF, I realised I don't know how to apply the explanations found on the Internet to my situation.
So, the formula found on the Internet is: the value of the ETF at the start of the year * the Basiszinssatz (0.07 % in 2020) * 0.7 * Kapitalertragssteuer and Solidaritätszuschlag (26.375 %).
All good, except, at the beginning of 2021 I had no portfolio since I started investing in April. So let's say I started buying a few ETFs (of the same kind) each month of 2021 until at the end of the year I ended up with 50 ETFs valued 5.000 euro. I didn't sell anything in the meantime.
How can I calculate the taxes I owe based on the above formula? I am totally at loss so any help would be much appreciated. Thank you.