A business includes within its T&Cs that in the event that Govts decide to increase the tax they impose on said business that business will seek to recover that additional tax.
Not sure what legal protection is required if a business is being clear in its Terms and Conditions
It's called goodwill to your customers, something which you and your employer are not prone to and long term will harm your business as people go elsewhere where they can. Customers do not like small print.