N.J. Admin. Code § 18:26-2.15
In the case of a nonresident decedent's estate containing real or tangible personal property located in this State that passes to a transferee wherever situated, except by means of a specific devise, the tax on such transfer is to be first computed on the entire estate as if the decedent were a resident of New Jersey and all of his or her assets were located in New Jersey and then prorated (multiplied) by the proportion (ratio) which the New Jersey real and tangible personal property bears to the entire estate.
Example: Mr. A, a California domiciliary, died intestate, on July 3, 2016, leaving as his sole heir a nephew, Mr. B. Mr. As estate consisted of the following: real property with a value of $ 10,000 in New Jersey; $ 20,000 cash located in an Illinois bank; and $ 70,000 of real and personal property located in California.
The New Jersey property is subject to the ratio tax pursuant to this section and the tax on such transfer is computed as follows: First, a tax is computed on the value of the entire estate as if such estate were located in New Jersey, (that is, $ 100,000 x 15 percent, the rate applicable for property passing to a Class "D" transferee or $ 15,000 tax). Second, the tax so computed is then multiplied by a fraction whose numerator is the value of the real or tangible personal property located in this State and whose denominator is the value of all property of the estate, real or personal, tangible or intangible, wherever situated (that is, 10/100 x $ 15,000 = $ 1,500 tax, which is the ratio tax on the property passing to Mr. B.).
If Mr. A had specifically devised the property in New Jersey to his nephew, said property would not be subject to the ratio tax, but rather, it would be taxed directly to the devisee at the New Jersey resident tax rates.
Example: Same facts as example above except that Mr. A died testate and bequeathed $ 10,000 held in a bank account to his nephew and the rest of his estate to his spouse/civil union partner/domestic partner. First, a tax is computed as if Mr. A had been a New Jersey domiciliary. Mr. B would be liable for $ 10,000 x 15 percent = $ 1,500 tax. All of the property received by Mr. As spouse/civil union partner/domestic partner would be exempt. Second, the total tax, $ 1,500, is then multiplied by 1/10, the ratio of the property subject to tax to the entire estate (1/10 x $ 1,500 = $ 150.00, the amount of tax due).
N.J. Admin. Code § 18:26-2.15