“Karma” refers to the cause and effect (on a person) of the actions, intents and deeds that that person undertakes. Bad karma is typically taken to mean you have not acted in a good way and – consequently - should be expecting some bad things to happen to you (in return for your poor deeds or actions).
I would question the “intent” of the thread originator as to whether the desire to report SUSPECTED tax evasion stems from genuine concern for the greater good. Add to that that we do not know the impact or consequences of any investigation on the SUSPECTED perpetrator.
Hence, the warning to be wary of incurring bad karma – and advice for the originator to contemplate (a) her motivations and (b) the robustness of her suspicions before proceeding.
The fact there is a thread in the first place surely implies the originator herself has SOME reservations about whether reporting her suspicion is appropriate? She has also admitted that disliking the person concerned is part of her motivation.
So, yes - I would caution thinking on this further.
With regard to HMRC. I am well aware of the mechanisms for reporting suspected tax evasion. I am also NOT suggesting HMRC would go out of its way to reveal the identity of the accuser.
However, the identity (or suspicion of identity) could emerge from other sources or causes.
Defamation happens when a false claim is made to a third-party other than the person defamed (wronged) and in the UK is legally split into slander and libel. So, if the SUSPECT is not tax-evading the accusation would be defamatory and would be inexcusable unless the accuser had had genuinely REASONABLE grounds for believing the accusation she makes. Depending on the motivations of the accuser and the damage done to the accused – i.e. the extent to which any HMRC investigation causes distress – this could be considered malicious conduct.
While most dealings with HMRC are fine, I have certainly had the odd past experience that has been very distressing (their errors not mine) and which they did not resolve rapidly.