A service code is only issued by TurboTax support and only for very specific reasons.
You do not need a service code to file a tax return, what you do need is a verification code.
See this TurboTax support FAQ for the verification code - https://ttlc.intuit.com/turbotax-support/en-us/help-article/security-risk/trouble-filing-verification-code/L6X76gZlE_US_en_US?uid=m5lls83e
@ezam11 wrote:How do I get a service code when completing my taxes
For what kind of issue? You'd have to talk to Customer Support about an issue you're having. If they can't solve it any other way, sometimes they will issue a service code. But they don't normally issue one just for requesting.