UIR stands for Unique Investment Reference and is an 8 digit number you receive from HMRC after you send them your SEIS or EIS1 Form, Cover Letter & Supporting Documents. It can also be referred to as a SEIS2/EIS2 number.
Below is an example of the email HMRC send back with the UIR/SEIS2 number:
Here are some guides you may find useful if you're doing your SEIS or EIS Compliance:
- How to do your Compliance on SeedLegals