The Green Lane, when it becomes operational, by the end of September 2024, will provide expedited access from GB into Northern Ireland solely for goods which are not at risk of moving to the EU. These goods must be for sale or final use in Northern Ireland. Perhaps you have noticed packaging in supermarkets with a new label stating 'Not for sale in the EU', this is in preparation for Green Lane movements, which should significantly reduce the administrative burden on NI companies.
In order to utilise the Green Lane, you must be UKIMS (Internal Market Scheme) registered and be able to declare the goods will not travel to the EU. Goods that are 'at risk' of moving to the EU must use the Red Lane and EU Duty must be paid but can be claimed back later if you can prove the goods never moved to the EU. There will still be the option to claim a customs duty waiver under the principle of de minimus state aid, on red lane goods, provided you are within the threshold.
Check out your de minimum state aid threshold here, it varies depending on sector:-
https://www.gov.uk/guidance/check-if-you-can-claim-a-waiver-for-goods-brought-into-northern-ireland
If you plan to use the NIAID code to claim state aid on duty on your at risk goods, don't forget you need to keep track of your total state aid over the past three years. Record any non-customs state aid on the HMRC Gateway, for example, if you are an SME you may be claiming Employment Allowance and this will go towards your total de minimus state aid in addition to your customs duty waivers and will need added manually on Govt Gateway.