I got in a fight with a roommate that I allowed to move in to my apartment. He gave me his 30-day notice and as the 30-day period was to end on Nov. 28, I told him he could use the two extra days as the 28th fell on Sunday after Thanksgiving. He paid his rent for the room on Nov. 4th. He then moved out on Nov. 13th unexpectedly but kept his apartment keys and didn't clean his room or do any cleaning of areas he had used, e.g. his half of the refrigerator, the patio. (When he moved in, he took over the whole ground-floor patio with his stuff.) The room he vacated was really unclean with the carpet needing to be replaced, with the blinds damaged and some scuff marks on the walls. He moved in without a security deposit. I am on a month-to-month type of rental arrangement with the apartment complex. He now wants a prorated portion of his share of the rent for the days he's not here. I told him his 30-day notice protected him but also me as it ensured I'd have his share of rent for the month until the 30-day notice expired while providing him the time he needed to find another place. Plus, I reminded him he left the patio and his room an absolute mess. The damages will require me to have to probably replace the carpet in his room and the blinds. Who is right?

... He paid his rent for the room on Nov. 4th. He then moved out on Nov. 13th ...
He now wants a prorated portion of his share of the rent for the days he's not here....
Who is right?

I wouldn't pro-rate a portion of the final 30 days. You are correct regarding how a 30-day notice is supposed to work. A landlord who gives a tenant a 30-day notice is entitled to the full amount of rent for that 30 days, even if the tenant moves out early. It's how a month-to-month tenancy works. And it is clear that he was a month-to-month sub-tenant.

Also, of course, in the absence of a security deposit, he will owe you for the full amount of the damages. If he fails to pay that your only option would be small claims court.

First any question on law needs to include your general local as laws vary by area. Some states do require pro-rating rents others do not. And the rules for pro-rating may vary. Since the tenant was the one giving notice he MAY have the right on pro-rating.

On the other hand, if you can prove damages greater than the pro-rated portion would be, then sue for the balance of those damages.

This is great info. Thank you very much. I appreciate it.

You can't charge him for a carpet that you think your landlord will replace when you eventually leave. Can you prove the carpet was not damaged before he moved in and that he did the damage?

This is great info. Thank you very much. I appreciate it.

You are welcome. But as ScottGemm said, we need to know what state you are in to determine if pro-rating is required.