(a) The recording of a supplemental mortgage is subject to the applicable mortgage recording taxes as described in Part 642 of this Title to the extent that such mortgage creates or secures a new or further indebtedness or obligation other than the principal indebtedness or obligation secured or which under any contingency may be secured by the prior recorded primary mortgage(s). (See Part 647 of this Title for the special treatment of credit line mortgages on certain residential property).

(b) For purposes of this subdivision, the principal indebtedness or obligation secured by or which under any contingency may be secured by the prior recorded primary mortgage is equal to the remaining principal indebtedness secured or which under any contingency may be secured by such mortgage at the time that the supplemental mortgage is executed or at any time thereafter.

On January 1, 1990, Mr. Jones gives XYZ Bank a mortgage securing a principal debt of $100,000 and the proper mortgage recording taxes are paid. On January 1, 1991, at a time when the remaining principal indebtedness secured by such prior recorded mortgage totals $90,000, Mr. Jones gives XYZ Bank another mortgage which secures an additional $30,000. When the mortgage was presented for recording the proper taxes computed upon the $30,000 amount were paid. Simultaneously, Mr. Jones and the bank enter into an agreement which by its terms and conditions consolidates the liens of the two mortgages into one lien securing a total principal debt of $120,000. The consolidation agreement makes proper reference to the prior recorded mortgages. Therefore, the consolidation agreement constitutes a supplemental mortgage which may be recorded tax free since it does not secure any new or further indebtedness other than that secured by the prior recorded primary mortgages.

If the new $30,000 mortgage had by its terms consolidated the liens of the two mortgages into one lien securing a total principal debt of $120,000, the new mortgage itself would have constituted a supplemental mortgage. The applicable mortgage recording taxes would apply to its recording and taxes would be imposed and computed based upon the $30,000 of new or further indebtedness secured by such mortgage.

(c) Notwithstanding any provision to the contrary in subdivisions (a), (d), (e) and (f) of this section, where a supplemental mortgage is recorded for one of the purposes set forth in section 645.1(a)(3) of this Part and the additional real property covered by the supplemental mortgage is situated in a county where the additional tax is currently imposed and the prior recorded primary mortgage is situated in a county where the additional tax is currently imposed and the prior recorded primary mortgage was on real property situated in a county that has suspended the additional tax, and such tax was not paid, such additional tax, as described in section 642.2 of this Title is imposed and computed based on the principal indebtedness or obligation secured by or which under any contingency may be secured by such supplemental mortgage on the date it is executed or at any time thereafter.

Mr. Smith gives Z Bank a mortgage on real property located in Schoharie County, which is a county that has suspended the imposition of the additional tax. The mortgage secures a principal debt of $50,000. The mortgage is recorded and the proper mortgage recording taxes are paid. Subsequent to the recording of such mortgage, Mr. Smith gives Z Bank a mortgage on real property located in Albany County, as additional security for the payment of the same $50,000 debt. Albany County imposes the additional tax.

The additional tax is imposed and computed upon the $50,000 debt secured by the supplemental mortgage.

(d) Notwithstanding any other provision to the contrary in subdivisions (a), (c), (e) and (f) of this section, where a supplemental mortgage is recorded for one of the purposes set forth in section 645.1(a)(3) of this Part, and the additional real property covered by the supplemental mortgage is situated within the City of New York, and the recorded primary mortgage was on real property situated outside such city and the City of New York tax as described in section 642.4 of this Title was not paid when the prior recorded primary mortgage was recorded, such mortgage recording tax is imposed and computed based on the principal indebtedness or obligation secured by or which under any contingency may be secured by such supplemental mortgage.

Same facts as in Example 2 except that the real property which is encumbered by the lien of the supplemental mortgage given as additional security is located in New York City, where both the additional tax and the City of New York tax are imposed, and the remaining principal debt secured or to be secured by the first mortgage at the time the supplemental mortgage is executed mortgage is $45,000.

The additional tax and the City of New York tax are imposed upon the recording of the supplemental mortgage and computed upon the $45,000 debt secured by such supplemental mortgage.

(e) Notwithstanding any other provision to the contrary in subdivision (a), (b), (c), (d) and (f) of this section, where a supplemental mortgage is recorded for one of the purposes set forth in section 645.1(a)(3) of this part, and the additional real property covered by the supplemental mortgage is situated within the City of Yonkers, and the prior recorded primary mortgage was on real property situated outside such city and the City of Yonkers tax described in section 642.5 of this Title was not paid when the prior recorded primary mortgage was recorded, such mortgage recording tax is imposed and computed based on the principal indebtedness or obligation secured by or which under any contingency may be secured by such supplemental mortgage at the date of execution of such supplemental mortgage or at any time thereafter.

(f) Notwithstanding any other provision to the contrary in subdivision (a), (b), (c), (d) and (e) of this section, where a supplemental mortgage is recorded for one of the purposes set forth in section 645.1 (a)(3) of this part, and the additional real property covered by the supplemental mortgage is situated within Broome County, and the prior recorded primary mortgage was on real property situated outside such county and the Broome County tax described in section 642.6 of this Title was not paid when the prior recorded primary mortgage was recorded, such mortgage recording tax is imposed and computed based on the principal indebtedness or obligation secured by or which under any contingency may be secured by such supplemental mortgage at the date of execution of such supplemental mortgage or at any time thereafter.