Positive commandment · Mitzvat Aseh #116 of 613
For a person who makes an endowment valuation concerning his home to give the value determined by the priest
להיות מעריך ביתו נותן כערך הכהן
The verse · Vayikra 27:14
וְאִישׁ כִּי־יַקְדִּשׁ אֶת־בֵּיתוֹ קֹדֶשׁ לַה׳ וְהֶעֱרִיכוֹ הַכֹּהֵן בֵּין טוֹב וּבֵין רָע כַּאֲשֶׁר יַעֲרִיךְ אֹתוֹ הַכֹּהֵן כֵּן יָקוּם
“And when a man shall sanctify his house to be dedicated to the Lord, then the priest shall estimate it, whether it be good or bad: as the priest shall estimate it, so shall it stand.”
The Rambam’s words
For a person who makes an endowment valuation concerning his home to give the value determined by the priest, as [Leviticus 27:14] states: "And the priest shall determine its value."
להיות מעריך ביתו נותן כערך הכהן, שנאמר: "וְאִישׁ כִּי יַקְדִּישׁ" (ויקרא כז, יד).
Why · Sefer HaChinuch #354
Appraising houses, such that he give the appraisal that the priest appraises and the addition of a fifth
“It is from the roots of the commandment that G-d, blessed be He, wanted to instill His fear in the hearts of people in all matters of sanctity, and as I wrote in the building of the holy House and its vessels in the Order of Vayikchu Li Terumah (Sefer HaChinukh 95).”
Who & when
“And [it] is practiced at the time that the Jubilee is practiced, as the law of appraisals of houses is only practiced — meaning to consecrate a house from the outset — at the time that the Jubilee is practiced.”
Where in the Mishneh Torah
Hilchot Appraisals and Devoted Property הלכות ערכים וחרמין