@Michelle Marian 

Is there a reason you can't record the deposits to Undeposited Funds ($2,000 in Dec. and $1,000 in Jan.) and then make the correct $3,000 deposit on Jan. 31?  That will accurately book $2,000 in cash transactions in Dec. and $1,000 in Jan. and the $3,000 deposit will match your bank statement.  Also, if you make a deposit entry in January that is dated December, it won't affect your December reconciliation.