61 Pa. Code § 91.157
(b) If the transfer merely changes the undivided proportionate interest of the cotenants, the value of the property is taxable to the extent of the proportionate change in ownership interest.
Example:
X, Y and Z each own an undivided one-third interest in Lot 3. X and Y each convey a one-twelfth interest to Z, leaving X and Y each with a one-quarter interest and Y with a one-half interest. As the grantors conveyed a one-sixth interest and the grantee received a one-sixth interest, the transfer is taxable on one-sixth of its value.
The provisions of this § 91.157 issued under section 1107-C of the Tax Reform Code of 1971 (72 P. S. § 8107-C).
The provisions of this § 91.156 adopted September 9, 1988, effective September 10, 1988, 18 Pa.B. 4096.