I do not know if there is a set 'rule' for checks that have not been cleared. Typically what I do is carry them over as outstanding until the end of my fiscal year. If at that time they are at least 6 months old, they may just be voided and written off. If they are not that old, I may just make an entry to move them into another GL account such as Bad Debt Expense or something along that line, depending on what the check is for and what is on your Chart of Accounts. You may also want to get in touch with the payee of the check to make sure that they received it. You do not want a vendor to come back later and say they were never paid. This can damage credit. Someone else may be able to answer this better because I have rarely run into this.
However, regarding payroll checks that have not cleared, I deal with this every year. I do not know if it is different from state to state, but in Texas you are required to send the money to the state comptroller after a period of time. This is considered 'unclaimed' money and is still owed to the employee. It is then kept on record with the state and can be claimed by that employee at any time. You can send an email to the State Comptroller and they will gladly respond or call you with all the details of what to do.
Hope this helps.
federal banking laws state that if a check is not cashed in 6mo the check is void. what you should do is reinstate the original entry with a reversal entry. As far as payroll checks are concerned your correct in stating that the amount should be turned over to the state agency that handles unclaimed funds.