UK Property Rental - 3% capital allowance

[MikeNew]

I found somewhere information that stated if I claim the 3% Capital allowance annually then this is later applied against Capital Gains taxes when the property is eventually sold, thus increasing CGT.

Can anyone tell me if this is true, or not, as my 'accountant' says claiming the 3% now has no affect on CGT in the future.

Also as the UK does not split land and building costs does anyone know the definitive method of calculation to be used?

Specifically:
Property cost - is it calculated at the exchange rate on date of purchase, the end of year (as for Modelo 720) or the average for the year (as for the income received during the year)?
Percentage of property costs used for the basis of the calculation - I have seen various figures quoted - from 50% to 70%

Thanks

[Granite]

I have been allowed 3% of 70% of the purchese price as declared on my Modelo 720. That figure will change each tax year in line with variations to the exchange rate compared to my Modelo 720 year of submission. However, given that I am still struggling with all the other isssues I mentioned in a previous thread "Tax Return" I am counting my blessings and using the same value each year. I have no knowledge of any CGT implications of claiming the "Amortización 3% coste de adquisisión" as an expense.