If you have created some intellectual property such as design for a product, or a software programme, why not allow your company to use it under a licence?
If this was someone else’s idea your company may well purchase it from them on a licence, so why not apply this to you as well.
The tax advantage is that there is no national insurance payable on the amounts paid under the licence. To make it legitimate, ensure that you don’t incur costs in developing this idea. To work out how much to charge for the licence you should contact a patent agent. It’s important that the charge is set at market value to avoid it being disallowed by the taxman.
Make sure you raise a sales invoice from you to the company. A licence agreement should be prepared. And don’t forget that the licence income needs to be disclosed on your tax return. If in doubt, ask an accountant.