When an IRA Transfer Request is initiated (for ex. 1/10/2008) and the bank receives the check (for ex. 1/30/2008) is the bank required by any IRS regulation that states that we have to use the first date that the Transfer Request was initiated as the issue date when we deposit the check and issue the customer their IRA/CD certificate? The customer is getting backdated accrued interest when we do this.
What do other banks do?
Is there an IRS regulation that states we have to do this?

The day we receive the check it is deposited into a new CD. If the Customer does not want to lose the twenty days interest they should have either had the check overnighted or hand delivered the check. We didn't have the funds for the 20 days in your scenario, so why should we pay interest? Presumably, the funds were sitting in another institution earning interest during this time.

No requirement to do so.

Your customers must be making out well... they are getting double interest for those lag days. You can be assured the other bank is not closing out the the IRA as of the effective date of the Transfer Request, and hence taking interest accured back.