Take it before a court of competent jurisdiction. Have your attorney file a Motion to Compel an Accounting. See Find-A-Lawyer at the top of this page. Good Luck!!
My answer is based on the limited facts presented. It doesn’t create an attorney-client relationship. Use the ‘Find-A-Lawyer’ search engine at the top of this page and follow proper legal advice.
There is an attorney who set up the trust, and who is responsible for the way the trust is structured.
The first place I would go, would be to call that attorney and ask about the procedure for obtaining an accounting of the trust. If you are a trustee, and a beneficiary, with a dispute with another trustee, and you both have duties with regard to the distribution of the res of the trust (the money, etc), then you both should have been aware of all of the distributions as this occurred. However, if there is a dispute among trustees as to how you would CHOOSE to distribute the res due to tax implications, the trust document should have some clause about resolving disputes among trustees.
That is where the drafter of the document can help. They can point to the information about how to resolve trustee disputes.
If you are the only two trustees, then I suggest that you consult an estates and trusts attorney, and, that , based on the nature of the trust, you try to compromise on the issue with the other trustee.
Be sure that any attorney you deal with has tax experience with estates and trusts, as this can be a complicated area, since both Federal and local tax implications may arise.
This does not constitute legal advice or the engagement of my services as an attorney.
First of all a "simple" trust is an IRS defined concept requiring the distribution if fiduciary income each year to the beneficiary. Accordingly, your first confusing statement is referring to "retained earnings" which is a GAAP concept attributable to corporate net income that is not distributed. So with the above two concepts set forth, what are you talking about here? If the trust owns stock in a corporation and a dividend was declared (ergo retained earnings being conveyed to the trust as the shareholder of the corporation) then this would be fiduciary income required to be distributed in a a simple trust structure. Absent knowing more facts about what you are referring to as well as reading the trust and understanding what it actually requires then impossible to answer your question, try repost your question with the info I gave you in mind so as to give a better context to Avvo attorneys to give you a decent answer.
My answer is not intended to be giving legal advice and this topic can be a complex area where the advice of a licensed attorney in your State should be obtained. Please click "helpful" or "best answer" if my answer added any value or add a "comment" if you have more info for me to help you get a better answer.