A non-material amendment application is required if you have already been granted planning permission but want to make a small change, such as moving a door or window. There is no statutory definition of what constitutes a non-material amendment, therefore, a judgement is made on a case by case basis.
If your proposed amendment is not considered to be non-material, then a variation of condition application will be required.
Variation of conditions
This is an application to amend the conditions on a planning permission and you can download the removal or variation of conditions application form here.
As with a full planning permission, all the necessary information must be submitted with an application for it to be valid. More information on validation requirements.