Hello rosie and welcome to JustAnswer. I am sorry to hear about the problems you are having.
The general statute of limitations for filing a felony in Colorado is three years from the date of commission of the offense. Colorado Revised Statutes section 16-5-401, subsection (1)(a).
However, the 3 year period starts upon the commission of the last act of any series of acts which violate the law. So, the date on which you last submitted documentation related to the 2005 year assistance, would start the 3 year SOL period. CRS section 16.5-401, subsection (4).
Furthermore, the SOL for theft does not start to run at all until the theft has been discovered. CRS section 16.5-401, subsection (4.5)(c). Therefore, the statute in your case would not start to run until the fraud was discovered.
Which, if any, of these exceptions would apply in your case, depends on the exact circumstances under which they discovered that you had not reported your prn income and when that occurred.
At this point, you absolutely have to consult with an attorney about this problem. If you cannot afford an attorney, you should ask the court
to appoint the public defender. You can do this when you go to court the first time (for your arraignment).
It is particularly important that you make your attorney aware that you were planning on entering the military, as a felony conviction may well prevent you from being able to do so.
Thanks for asking your question here on JustAnswer and good luck dealing with this problem. If you have any other questions, please let me know.