location: California
We signed a fixed-term lease a few months before moving into a house in August.
The lease states a monthly rent and says that August would be prorated. A signed addendum then gives a specific dollar amount for the prorated August rent.
We paid exactly the amount stated in the signed addendum before moving in. The landlord accepted the payment and did not raise any issue at the time.
Now, more than a month after we moved in, the landlord says he discovered that the August amount written in the addendum was calculated incorrectly. He recalculated the prorated rent based on the number of days we occupied the house and is asking us to pay the difference.
His new calculation appears mathematically correct, but the lower amount was specifically written into the addendum that both parties signed, and we paid exactly what the agreement required.
Under California law, can a landlord retroactively require us to pay the difference because the amount in the signed lease/addendum was a calculation error, or does the specific amount in the signed agreement control?