Do I pay CIL on a replacement dwelling?
Yes. It is a new dwelling and so incurs a CIL charge. However, you will be able to deduct the demolished floorspace from the new floorspace, providing it has been in lawful use for six months in the previous three years. You will pay CIL on any remaining floorspace. For example, if you demolish 100sqm of floorspace, and the replacement dwelling is 150sqm, you will pay CIL on the 50sqm. (150sqm(new)-100sqm(old)=50sqm)
Do I pay CIL on a barn converted into a dwelling?
Yes. It creates a new dwelling and so incurs a CIL charge.
If the barn, or part of the barn, has been in lawful use for at least six months in the last three years prior to development then CIL is not liable on the existing floorspace. The lawful use would need to be evidenced by providing appropriate evidence such as Council Tax records or business rates documentation.
However, if it has not been in lawful use, then CIL is liable on the full existing floorspace.
In either case, if an extension is being built on the barn, then CIL will be payable on the new floorspace.
More details can be found in the General Permitted Development Order 2014 (external link).
Is CIL chargeable on sub-division of an existing residential dwelling into two or more dwellings?
No. Any change of use to a building previously used as residential to create one or more separate dwellings is not liable for CIL, even if the house has been vacant.
I want to build a dwelling with usable loft space. Do I need to pay CIL on the loftspace?
Yes. If the loft floorspace is to be usable, and entered regularly, then CIL is liable.
I received planning permission for a development but now want to vary the application / conditions. Is CIL liable?
Potentially. Under a S73 application, any additional floorspace created through the new permission will be liable for CIL.