The first suggests a house you are planning to rent from someone else for your own use (although the insertion of the word "my" suggests you own it which ends up giving a bit of a mixed message). The second suggests you own the house and are planning rent it to someone else for their use. Most often with this kind of thing, you would say: " I am planning to rent a house ," if you are renting a house from someone else for your own use; or you would say: " I am planning to rent out my house ," if you are planning to take a house that you own and allow someone else to rent it from you for their use.
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