Offsetting Gains and Losses

We are working through a house transaction as a result of the death of my parents. my father died a number of years ago leaving 25% of the house to each of the 2 children, this value is in scope for CGT based on the probate/market value at the time of his death and sale value my mother died more recently and the remaining 50% of the property gets split between the 2 children, there is no CGT on this value as the property transfer is calculated in the IHT calcs and is selling below that value. On sale the property sells below the probate value for my mother's death but above the probate value from my father's death can the CGT liable on the 'gains' from the first tranche of ownership be offset with 'losses' on the property selling below probate from the second tranche or ownership. the entire property will be disposed of in one transaction.

Hi,
Capital Gains tax is a separate tax to Inheritance Tax. Both taxes may be payable depending on the size of the estate and the gains from the disposal of the property.
To work out the acquisition cost will have 2 calculations. As there are 2 beneficiaries, they each should work out 25% of the probate value when your father died and 25% of the probate value when your mother died. This will give each beneficiary a value for 50% of the property. This should be deducted from 50% of the disposal value to work out if there is a gain. if, after deducting costs and the annual exempt allowance, there is still a gain, this is taxable and should be reported and the tax paid within 60 days of the completion date.  
There is a capital gains calcuator below which leads on to registering for a capital gains account, to report and pay the tax due:
Tax when you sell property
Thank you.