I am filing 1040X as Single and am entitled to refund.

Few years back I filed as "Married Filing Separately", and my marriage was Annulled by the Courts due to fraud.

What documents to attach?

Do I attach the Certificate from the Court?

Do I attach a copy of the return filed for that year?

And what explanation do I give in Part III, what wording should I use?

Do I attach the Certificate from the Court?=====>>I THINK SO; obtaining an annulment means a change in your federal tax obligations DUE TO FILING STATUS CHANGE. you should file amended returns to correct the mistakes that were made on your original returns. No worry no penalty in attaching the certificate.



Do I attach a copy of the return filed for that year?====>>no;you need to attach only 1040x, not the whole prior return.

And what explanation do I give in Part III, what wording should I use?====>> The IRS needs to know why you are filing Form 1040X. For example, you have changed your filing status from mfs to single or etc. you may briefly describe your tax related situation