when is CGT applied on trigger , or on actual sale

[jakuk]

If there is a multi party agreement for a joint development of land.

At what date would CGT become applicable,

A) is it when final planning permission has been issued.

Or

B) When the development has started to be sold off ,

Or some other time entirely

[bd6759]

Development of land suggests a trading activity. You would pay income tax, not capital gains tax, on the profits.

[AnthonyR]

Aside from bd's point above that this may be trading (which will depend on your participation on the project)...

The date of disposal for CGT purposes is where you have an unconditional contract for sale.

This means that if you have a developer who is going to buy it from you subject to you getting planning permission, the tax point is when you get planning permission and the contract becomes unconditional (even if you don't get paid for some time afterwards).