(1) "Estimated amount due" for a school year shall mean the result of the following calculation:

The high school district's maintenance and operations excess levy that was certified as collectible for the calendar year in which the school year ends is divided by the estimated number of average annual full-time equivalent (AAFTE) students who reside within the boundaries of the high school district. That quotient is multiplied by the estimated number of AAFTE nonhigh district students enrolled in the serving high school district during the school year as reported on Form P-213.

(2) "Actual amount due" for a school year shall mean the result of the following calculation:

The high school district's maintenance and operations excess levy that was certified as collectible for the calendar year in which the school year ended is divided by the actual number of AAFTE students who resided within the boundaries of the high school district. That quotient is multiplied by the actual number of AAFTE nonhigh district students enrolled in the serving high school district during the school year as reported on Form P-213.

(3) "Estimated number of AAFTE students who reside within the boundaries of the high school district" during a school year shall mean the result of the following calculation:

Average the total number of AAFTE students served by the high school district reported on the Form P-223 available at the time of the calculation of the nonhigh billing. Subtract from this average the average number of AAFTE students attending the high school district's cooperative programs and reported as nonresident on Form P-223 available at the time of the calculation of the nonhigh bill. Also subtract all the estimated AAFTE nonhigh enrollment served by the nonhigh district as reported on Form P-213. Add the average number of AAFTE students who reside within the high school district who are attending cooperative programs in other school districts as reported on Form P-223 available at the time of the calculation of the nonhigh billing.

(4) "Actual number of AAFTE students who resided within the boundaries of the high school district" during a school year shall mean the result of the following calculation:

Subtract from the total AAFTE served by the high school district for a school year as reported on Form P-223 the nonresident AAFTE students served by the high school district for a school year as reported on Form P-223. Also subtract the actual AAFTE nonhigh enrollment served by the high school district as reported on Form P-213. Added to the resident enrollment count of the high school district is the number of AAFTE students who reside within the high school district who attended cooperative programs in other school districts and were reported as nonresident on Form P-223.

(5) "Nonhigh billing" shall mean the amount due to a high school district from a nonhigh school district for educating and transporting nonhigh district students.

(6) "P-213" shall have the same meaning as this is given in WAC 392-139-230.

(7) "Average annual full time equivalent students (AAFTE)" shall have the same meaning as this is given in WAC 392-121-133.

(8) "Annual determination of the excess maintenance and operation levy transfer from the high school district to the nonhigh school district for educating nonhigh school district students" shall have the same meaning as this is given in WAC 392-139-340.