。
I'm planning to move next month.
Literal
Next-month [at-に-は] move [schedule-予定] is.
The には stack (に + は) topicalizes the time word — 'as for (by) next month, the plan is to move.' It carries a subtle contrast 'as for next month (in contrast to other times).' A small but meaningful particle nuance: bare 来月に reports a schedule neutrally, while 来月には foregrounds 'next month' as the relevant time frame.