In that case your post was very badly worded. You responded to someone eho said: "Tax is a legal obligation not a moral one", and replied with: "No-one has said otherwise". You weren't specific about which part you were replying to, and many people have openly said this issue is also a moral obligation, so it was a natural assumption on my part.
The full text of what I responded to was "Tax is a legal obligation not a moral one, jesus. Pay what you owe, not a penny more and let the tax inspectors do their job." Apology accepted.