Many companies pay their owners / directors in dividends(assuming the directors are shareholders in many companies either because they are closed companies or get share options. No National Insurance is paid on the dividends albeit it is naturally income. Repeal this tax break to increase revenue and decrease inequality of treatment of income.
Why does this idea matter?
If all incoming monies were treated equally and transparently then Customs and Revenue costs of administration would drop (currently taxation is so complex that those with resources artfully dodge paying any tax), loopholes closed so more revenue is raised and the public who generally do not benefit from these tax dodges would feel they are getting more equitable treatment.