For the purpose of calculating capital gains tax on real estate, what acquisition price should be taken into account when the property was purchased under a life annuity arrangement?

As a rule, the acquisition price to be considered is the amount you actually paid, namely the lump sum (bouquet) together with the total amount of annuity payments made up to the seller’s death.
However, the tax authorities offer an alternative to the taxpayer: it is possible to use the value of the property indicated in the deed of sale (BOI-RFPI-PVI-20-10-20-10 §80).