Field help (RULTPFDAT) 

The rule concerning the valuation of the professional or property tax bases, applies only to the assets with the holding type In the property and for which the purchase date falls before or at the same time as that specified in this field.
For the other assets, their tax basis will be equal to the contirbution value.
This field is filled by default with the following value: 31/12/YYYY (where YYYY represents the year of the transaction effective date - 1).
This non-editable date must fall before or at the same time as the effective date.