رقم ضريبي مكلف = رقم الضريبة للمكلف بها = رقم تعريف المكلَّف بالضريبة
taxpayer ID no / or tax identification number /
taxable person account/ID number (this term made up by me) However "taxable person" and taxpayer both means مكلف بالضريبة

رقم ضريبي معفى = رقم الضريبة للمعفى منها= رقم الإعفاء الضريبي
tax exempt number / or tax exempt identification number

https://en.wikipedia.org › wiki › Taxpayer_Identification_Number
Taxpayer Identification Number
A Taxpayer Identification Number (TIN) is an identifying number used for tax purposes in the United States and in other countries under the Common Reporting Standard.In the United States it is also known as a Tax Identification Number or Federal Taxpayer Identification Number.A TIN may be assigned by the Social Security Administration or by the Internal Revenue Service (IRS).