Do you have a pending Domestic Relations case (divorce or paternity action)? If so, pursuant to the Florida Family Law Rules of Procedure, she is required to provide you with a long list of financial documents, including W2's, income tax returns, all proof of earned income, bank records, etc. Retain an attorney to represent you in this, and they will prepare a Request to Produce all the documents subject to mandatory disclosure, and do a Motion to Compel if she fails to comply.
As Ms. Cryer suggested, the answer is yes if there is a pending domestic relations case.
You should consult an attorney for advice regarding your individual situation since every case is different and not all information is relayed in an online question. The Law Office of Ophelia Bernal-Mora, P.A. is a family & criminal law firm located in Orlando, Florida, we invite you to contact us and welcome your calls at 407-377-6828. Contacting us does not create an attorney-client relationship. Please do not send any confidential information to us until such time as an attorney-client relationship has been established.
There are ways to get that information with the assistance of an attorney. If you have a pending Modification you should be able to obtain that information with a Request to Produce. Consult with a local attorney who can advise you as to your options.
Contact through this site alone does not establish a client lawyer relationship. This information is not to be used as a substitute for consulting with an attorney. I or any of the attorneys at longwelllawyers would be happy to give a free consultation. Call 407-426-5757. Longwell Lawyers
I agree with what the attorneys have said, and you might also consider sending a subpoena to her employer. I can help you with that, if you would like to call or email me.
The contents of this answer should be considered friendly advice, not legal advice (I'm a pretty friendly guy), and the answer should not be construed to constitute an attorney-client relationship. If you'd like actual legal advice, call me for a free consultation at 813-635-0222. Also, if you liked this answer as much as my big ego thinks you did, be sure to click the thumbs-up button!
You won't get it from the IRS, unless you are in the middle of a court hearing, or one of the other narrow exceptions that applies to the general anti-disclosure statute irc section 6103.
Please note that this is not legal advice, and should not be relied upon as such. Always consult with a competent tax professional to discuss your specific situation!