Updated: Updated to mention the introduction of employer Class 1A NICs on Sporting Testimonial payments above £100,000 will now take effect from 6 April 2019.
This measure confirms that all income from sporting testimonials and benefit matches for an employed sports person will be chargeable to tax, and National Insurance contributions (NICs) subject to a ‘one-off’ exemption of £100,000 of the income received from events held during a single testimonial or testimonial year.
Update
On 2 November 2017 the government announced that the introduction of the National Insurance Contributions Bill will be delayed.
The introduction of employer Class 1A NICs on Sporting Testimonial payments above £100,000 will now take effect from 6 April 2019 rather than 6 April 2018.
Source: HMRC