Notwithstanding the provisions of Section 45041, the governing board of a school district may adopt an alternative method of computing the salary received by a person requiring certification qualifications who serves less than a full school year.

Such method shall include the deduction from the employee’s regular salary of only that amount actually paid to a substitute or, if a substitute is not employed, the amount which would have been paid to a substitute had a substitute been employed.

For the purposes of this section, the amount which would have been paid to a substitute is that amount established by the district in a published salary schedule for substitute employees.

Such alternative method shall only be applied upon authorization by the school board based upon individual employee application and shall be limited to no more than five days per school year for each employee.