ANSWER:

Yes, you will be sinful and it’s a major sin.

https://islamqa.info/en/answers/112175/ruling-on-working-as-an-accountant-in-companies-institutions-and-factories

Honourable sheikh it is said that one who pays, receives and bear witness to payment of interest is equally sinful. My doubt is who all are included in the witness. If I’m an accountant of a company (not a bank) will I be sinful for preparing the accounts of my company.