It seems that HMRC take on average 6-8 weeks to approve an SEIS or EIS application, for both Advance Assurance and Compliance.
They tell us that simple applications (simple in that the company hasn't been trading yes, there are no complex subsidiaries, etc.) are approved quite quickly, but EIS applications for millions of Pounds in Advance Assurance can take up to 8 weeks.
We're seeing typical approval times of 3-4 weeks for applications done using SeedLegals.
There are two ways you can reach HMRC:
1. Email firstname.lastname@example.org
Use the same email the application was originally sent with.
It may take 2 weeks for them to reply
2. Phone 0300 123 1083
They no longer have a direct line therefore you can leave a message and they will determine whether a call back is required.