Prorating a 6 month lease
When writing a 6 month lease with move in date on 15th of the month, what should be the end date?
You can do move-in/move-out dates any day of the month you want. Additionally, you can have rent due any day of the month you want. I prefer to have my leases pro-rated to always have rent due the 1st of the month and likewise prefer to have leases end at the end of the month too, but it really doesn't matter. It's all what you agree with your tenant. I only do that so it's easier for me to track multiple rentals.
If you anticipate that the tenant will stay longer than 6-months, I suggest having the lease end at the end of the month so effectively 6.5 month lease to make it easier when you extend.
14th of the 6th month? Generally people aren't sticklers to that sort of thing. Best to talk to the tenant and ask if that is an okay end date. Not worth it to haggle over a few days. Most of the time they'll stay past the end of the lease term anyway, in my experience.