Tax avoidance
Tax avoidance reduces government revenue, so governments with a stricter anti-avoidance stance seek to prevent tax avoidance or keep it within limits. The obvious way to do this is to frame tax rules so that there is a smaller scope for avoidance. In practice this has not always been achievable and has led to an ongoing battle between governments amending legislation and tax advisors finding new scope/loopholes for tax avoidance in the amended rules.