There is not a formal template to follow. Why are you "cashing" a tenant's security deposit? As a landlord, you are basically to hold on to the security deposit in a separate account in trust to cover for damages or non-payment of rent. You are not to use that money. It is similar to putting money into an escrow account or an attorney putting money into a law firm trust account. Only upon a tenant not paying rent or causing damages beyond normal wear and tear are you allowed to apply the money for other purposes. In that situation, you need to send a letter to the last known address of the tenant along with an itemized bill of why you are withholding the funds and stating the reasons for doing so and return any funds that you are not applying to damages. Otherwise, the tenant can come after you for treble (triple the amount of the deposit) damages.
From your discussion of small claims court, I take it that the tenant has damages or has not paid rent. You just need to send that letter (which I recommend to be done by certified mail with return receipt) to the tenant. Then, you are covered. There is not a waiting period after then to file a small claims case for any additional damages.
I hope this helps. Sorry for the beginning part, I just wanted to advise you about how to handle future security deposits.
As accurately noted by my colleague Mr. Leroi, you must be careful and there are various issues at play if you plan to hold onto any portion of a security deposit.
Your primary obligations flow from you lease terms and the Colorado security deposit statute. Read that and understand every letter if you want to avoid being counter sued for violations. Here it is http://www.michie.com/colorado/lpext.dll?f=templates&fn=main-h.htm&cp=
You are strongly advised to speak with a landlord tenant attorney if you have questions and to make sure you understand the process and the required documentation. Making a mistake here will just appear in court when the counter sue for possible violations. Good luck.
This answer is for informational purposes only and is not legal advice regarding your question and does not establish an attorney-client relationship.