California Code, Revenue and Taxation Code - RTC § 5096.1

Except as hereinafter provided, taxes collected on behalf of a local agency from a taxpayer whose property has been annexed to a second local agency but was not detached from the first local agency due to error or inadvertence shall be deemed to have been erroneously collected for purposes of Section 5096 if the governing board of the first local agency makes a finding by resolution that detachment proceedings were not commenced due to excusable neglect. If the first local agency is a fire protection district the governing body of the annexing agency may make the finding by resolution that detachment proceedings were not commenced following annexation due to excusable neglect. For purposes of determining the amount of the refund the property shall be deemed to have been detached from the first local agency on the date annexation proceedings were completed.

This section shall not apply to taxes which would be collectible under authority of Government Code Section 56492 even though the annexed property had been detached from the special district.