It depends. If you are using Quick Employer Forms for W-2s, which could be one size, while the 1099-NEC could be another size.
If you are printing the forms you will be able to order the right sizes for each type so that the window for the address is in the correct place on the envelope.
Please update here if you have additional questions. This link could be helpful: QuickBooks Business Envelopes
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"