Legal Question in Real Estate Law in California

Unpaid rent can be subtracted from a security deposit. The landlord must act reasonably to mitigate the damages; having only ten days to rent the unit out is unreasonable. Several days are normally used up in doing a back ground check, the mailing of the proposed rental agreement, etc. It is not likely that a good tenant prospect would appear within a few days, especially since a good tenant would give thirty days notice to their landlord but probably would not do so until they found a new place to live. You tied the unit up for a week so that no rental could occur durring that time. You can not argue that the landlord should have found someone within ten days but that that you tied up seven of those days is immaterial.

You can sue in Small Claims Court, but I suspect you will lose

I assume that in addition to paying a security deposit that you also made some kind of lease or rental agreement, probably in writing. If there was no agreement having the effect of committing the landlord's space to you, you'd probably be entitled to refund of most, if not all, of any deposit you made. However, if you effectively tied up the apartment and thereafter changed your mind, I'd think most Small Claims judges would give the landlord a reasonable opportunity, probably more than a month, to find a new tenant at your cost, as reasonable damages for your breach of the agreement. The landlord's right to dock your deposit for damages is limited to his actual damages (lost rent, re-advertising costs, and the like) and so you may be entitled to a somewhat greater refund if the unit is re-rented at the same or greater rent before December ends.