§ 22. Building loan contract. A building loan contract either with or without the sale of land, and any modification thereof, must be in writing and duly acknowledged, and must contain a true statement under oath, verified by the borrower, showing the consideration paid, or to be paid, for the loan described therein, and showing all other expenses, if any, incurred, or to be incurred in connection therewith, and the net sum available to the borrower for the improvement, and, on or before the date of recording the building loan mortgage made pursuant thereto, to be filed in the office of the clerk of the county in which any part of the land is situated, except that any subsequent modification of any such building loan contract so filed must be filed within ten days after the execution of any such modification. No such building loan contract or any modification thereof shall be filed in the register's office of any county. If not so filed the interest of each party to such contract in the real property affected thereby, is subject to the lien and claim of a person who shall thereafter file a notice of lien under this chapter. A modification of such contract shall not affect or impair the right or interest of a person, who, previous to the filing of such modification had furnished or contracted to furnish materials, or had performed or contracted to perform labor for the improvement of real property, but such right or interest shall be determined by the original contract. The county clerk is entitled to a fee of twenty-five dollars, except in counties within the city of New York where the fee shall be fifty dollars, for filing such a contract or modification. Except where the county clerk maintains a block index, such contracts and modifications thereof shall be indexed in a book provided for that purpose, in the alphabetical order of the names of the persons to whom such loans shall be made. No assignment of the moneys due or to become due under a building loan contract, under the provisions of section twenty-six of this article, nor any payment to the holder of such assignment, shall be or be construed to be a modification of a building loan contract within the meaning of this section, and the execution and delivery of a bond and mortgage, under the provisions of section twenty-six of this article, or payments thereunder, shall not be or be construed to be the making of a building loan contract within the meaning of this section.

Except that this section shall not apply to any mortgage taken by the home owners' loan corporation, a corporation created under an act of congress, known as the "home owners' loan act of nineteen hundred thirty-three" and the "home owners' loan act of nineteen hundred thirty-three as amended," and said mortgage shall have priority over any and all liens filed subsequent to the date of the recording of said mortgage whether or not the cash and/or bonds for which said mortgage has been taken as security, shall have been advanced at the time of the execution of such mortgage or subsequent thereto, and it shall not be necessary to execute and file any building loan contract or any other contract, in compliance with this section or any part thereof.

Where the county clerk indexes liens in a block index, every building loan contract presented to the clerk for filing, in order to entitle the same to be filed, shall contain in the body thereof, or shall have endorsed thereon, a designation of the number of every block, on the land map of the county, which is affected by the building loan contract. The county clerk shall cause such building loan contract to be entered in the block index, under the block number of every block so designated. In cases where a building loan contract shall have been filed without such designation or with an erroneous designation, the county clerk, on presentation of proper proof thereof, shall enter such instrument in the proper index, under the proper block number of every block in which the land affected is situated, and shall, at the same time, make a note of such entry and of the date thereof in every place in which such instrument may have been erroneously indexed, opposite the entry thereof, and also upon the instrument itself, if the same be in his possession or produced to him for the purpose, and the filing of such instrument shall be constructive notice as to property in the block not duly designated at the time of such filing only from the time when the same shall be properly indexed.

A county clerk may adopt a new indexing system utilizing electro-mechanical, electronic or any other method he deems suitable for maintaining the indexes.