If you are non US citizen who has US source income, you are required to get a TIN to file your taxes and get any refunds due. Now, the TIN can also be used in place of the SSN to open bank accounts and get credit.
-- Bank of America, Wamu etc.. will take a mexican consular (Matricular) card and a TIN to open bank accounts, get credit cards and even get a mortgage. In fact you can walk into any branch with just your foreign ID and the bank will actually fill out and the submit the TIN form for you.
When paypal asks for a SSN they most likely run a Dtect, (soft credit check), a Dtect will show the names and addresses associated with any past credit given for that SSN or TIN.
I worked for credit-collections company for 6 months a few years ago so I know this to be fact. When they would send us collections files where the person had skipped or there was a whiff of fraud, the first step was always to run a dtect, to find out who the ssn/tin really belonged to and get new addresses from which we could do further tracing. That is because the credit bureaus only charge a $1 for a detect and $5+ ( depending on volume) for a full report. --
I doubt Paypal would pay the full fee (especially on a limitation or debit card issuance), so they almost certainly run a dtect on any SSN or TIN you supply. If the number has an address and name that is kosher with the info you gave them, there should be no problem.
But that's why the SSN/TIN is such a problem to overcome if you want to stay white hat.
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