Your Taxpayer Identification Number is probably the most important information you deliver to the requester when completing a W-9. Still, it might be not easy to understand what type of TIN you have to use. So, lots of questions like “do I have to give my SSN on W-9?” or “can I use an EIN for a W-9” appear. This guide is aimed to give you all the answers and to explain what kind of TIN you have to enter.
TIN types that can be used in the document
The following spreadsheet will give you a full information on the topic
| Type | Who can use it? | Details |
| SSN | Individuals | Social Security Number can be found in your Social Security Card. It is used as TIN mostly by individuals. |
| EIN | Business entities like corporation, LLC, partnership etc | Employer Identification Number is assigned to a company by IRS. |
| ITIN | Resident alien | A resident alien has to use it when completing the form. |
| ATIN | Adopting taxpayers | ATIN is a temporary substitute for an adopted child’s SSN. |
| SSN or EIN | Sole proprietor | You can use one of available options. |
| Owner’s SSN or EIN | Single-member LLC disregarded entity | Do not use entity’s EIN. |
Follow the above-mentioned instructions to deliver a correct TIN to the requester. Make sure you’ve given a right number. Mistakes may be a reason for penalties from IRS.
Does your TIN number on W-9 stay the same?
Actually, there are several situations when it can be changed. One of them is when companies alter their structure. In this case they’ll get a new EIN. You can find full instructions on the topic for every entity type on IRS website.
If your TIN was changed, you have to send a new blank with updated information to every requester. Do it as soon as possible so that you won’t become a subject to backup withholding or penalties from IRS.
How to get a TIN?
What if you don’t have Taxpayer Identification Number? In this case you should get it as soon as possible. Use Form SS-5 to apply for SSN or form SS-4 to get EIN. But what about residents alien? They often ask “can undocumented people submit a W-9 with ITIN number or they have to apply for SSN?”. As it was mentioned earlier, they should use ITIN. If a resident alien doesn’t have one, then Form W-7 should be used to apply for it.