The best and quickest method is to have a copy notarized unless you can get a certified copy of your tax return directly from the IRS with an official signature that can be verified at the US Department of State.
You can ask your accountant to have his or her signature signed and notarized, or you can visit a nearby notary public to get your signature signed and notarized. Please confirm whether you or your accountant are permitted to vouch for the veracity of the transcripts with the country making the apostille request. In the absence of that, you must get in touch with the IRS and ask for certified and signed transcripts.
Using Form 4506, you have the opportunity to ask for certification of a copy of your tax return. By checking the box on line 6, you request the certification.
Please let us know whether you also need to apostille your W2.
The top provider of document certification, legalization, attestation, and apostille services is Visa Express Inc.
Apostilles may be challenging. Don't trust this technique to untrained workers or unqualified individuals who are unaware of the Apostille procedure and the particular needs of several countries. Your paperwork can be turned down, which would cost you time and money. Be awared!