Legal Question in Real Estate Law in California

Re: Default Notices

First, any lease with a purchase option should be in writing. Assuming yours is in writing, you should look for the provisions that define what is a default and what the non-defaulting party's remedies are. Usually, the written provisions of a contract (such as a lease with option to purchase) will prevail over general legal principles regarding default.

However, if there are no applicable written provisions, being 10 days late in payment of rent is a default. Most landlords would overlook it, or invoke only the late-payment penalty provision (if any).

Having said that, I wonder if the issue is not whether you have lost the right to exercise the purchase option as a result of being 10 days late. My answer would be that if you are 10 days late in exercising the option, you've lost the opportunity. However, if you're 10 days late in paying rent, you have a good chance of prevailing against the landlord/seller's claim that you have forfeited the right to exercise the option in the future (if that's the issue).

If indeed your question concerns loss of the right to exercise the option at some future time, you should see a real-estate lawyer at once.

The exact wording of your lease-option will be very important in the outcome.