What an ITIN is, in this context
An Individual Taxpayer Identification Number is issued for tax-filing purposes. For a lender the relevant fact is narrow and practical: it is how this borrower files and pays taxes, and therefore how their income can be documented.
That is the whole of it here. This is a documentation question about how a file gets built, and nothing on this page addresses anything else.
Why the answer is so often no
Most retail lending is built around a Social Security number because the systems assume one, credit pull, identity verification, automated underwriting. Where the software has no field for what you have, the answer comes back no, and it comes back quickly.
That is a statement about the channel, not about the borrower. Lenders who write these files have a process built for them rather than an exception to one.
What carries the file instead
Tax returns filed under the ITIN, documented income, and the down payment with its source evidenced. Where there is limited traditional credit history, alternative evidence of paying obligations on time (rent, utilities, insurance), can often be assembled instead.
The work is in the documentation, and it is worth starting early because pulling several years of records together takes longer than people expect.
What to send
How you file, how your income arrives, and what you are trying to buy. That is enough for a straight answer about whether the file assembles.
Where this is a consumer mortgage I originate it in select states. Eligibility and terms vary by scenario and by lender guidelines; nothing here is a commitment to lend.