1. Line 1. Enter the gross or potential income of each party.
2. Line 2. Subtract the amount paid by each party under previous child support orders for other child(ren) of that parent, and enter the difference (monthly adjusted gross income) for each parent.
3. Line 3. Divide each parent's monthly adjusted gross income by the combined monthly adjusted gross income and enter each parent's percentage share of the combined income.
4. Line 4. Enter the amount of the basic child support obligation for the child(ren) for whom support is sought by using the Schedule of Basic Child Support Obligations based on the combined income of both parents and the number of children involved in the pending action.  If the non-custodial parent's income falls within the shaded area of the Schedule, determine the basic child support obligation based on the non-custodial parent's monthly adjusted gross income, rather than the combined income of both parties.

N.C. Admin. Office of the Courts, N.C. Child Support Guidelines, AOC-A-162, Instructions for Worksheet A (1998).

After applying steps one through four above, the following procedure is used to finalize the child support calculation as per Worksheet A of the Guidelines:

5. Line 5a through 5c. Enter the amount of work-related child are costs, health insurance premiums for the child(ren), and extraordinary child-related expenses that are paid by either parent under the column for that parent. 
6. Line 5d. Enter the sum of lines 5a through 5c for each parent, and in the third column (Combined) enter the total expenses paid by both parents.
7. Line 6. Add line 4 and line 5d (Combined) and enter the result (total child support obligation).
8. Line 7. Multiply line 6 by line 3 (percentage share of income) and enter the result in the appropriate column for each parent. 
9. Line 8. Enter the amount of expenses paid directly by the non-custodial parent (line 5d) under the appropriate column; leave the custodial parent's column blank and do not enter any amount paid by the custodial parent.
10. Line 9. Subtract line 8 from line 7 for the non-custodial parent only and enter the difference (recommended child support order) under the column for the non-custodial parent.  Leave the column for the custodial parent blank.

N.C. Admin. Office of the Courts, N.C. Child Support Guidelines, AOC-A-162, Instructions for Worksheet A (1998).

Support as per Worksheet B, after following steps one through four above, should be further calculated as follows:

5. Line 5. Multiply line 4 by 1.5 and enter the result.
6. Line 6. Multiply line 5 by each parent's percentage share of income (line 3) and enter the result under the appropriate column for each parent.
7. Lines 7 and 8. Enter the number of nights the child(ren) spend with each parent during the year and calculate the percentage of total overnights spent with each parent. If the child(ren) does not spend at least 123 overnights with each parent, Worksheet B should not be used. 
8. Line 9. Multiply plaintiff's line 6 by defendant's line 8 and enter the result under the column for plaintiff, then multiply defendant's line 6 be plaintiff's line 8 and enter the result under the column for defendant.
9. Lines 10a through 10c. Enter the amount of work-related child are costs, health insurance premiums for the child(ren), and extraordinary child-related expenses that are paid by either parent under the column for that parent. 
10. Line 10d. Enter the sum of lines 10a through 10c for each parent, and in the third column (Combined) enter the total expenses paid by both parents.
11. Line 11. Multiply line 10d (Combined) by line 3 for each parent and enter the result under the column for that parent. 
12. Line 12. Subtract line 11 from line 10d for each parent and enter (if negative, enter zero).
13. Line 13. Subtract line 12 from line 9 for each parent and enter the result on line 13 under the appropriate column.  In some cases, the result may be a negative number. If the result is negative, enter it as a negative number on line 13, not as a positive number or as a zero. 
14. Line 14. If plaintiff's line 13 is greater than defendant's line 13, enter the difference between these two amounts on line 14 under plaintiff's column and leave defendant's column blank.  If defendant's line 13 is greater than plaintiff's line 13, enter the difference between these two amounts on line 14 under defendant's column and leave plaintiff's column blank.  [Note that if either of the numbers on line 13 is a negative number, you must change the signs when you subtract. For example, $100 minus negative $50 equals $150.]

N.C. Admin. Office of the Courts, N.C. Child Support Guidelines, AOC-A-162, Instructions for Worksheet B (1998).

Support as per Worksheet C, after following steps one through four above, should be further calculated as follows:

5. Line 5a. Enter the number of children living with each parent and the total number of children for whom support is sought.
6. Line 5(b). Divide the number of children living with each parent by the total number of children and enter the result in the appropriate column for each parent.  (For example, if there are three children of the parties and one child lives with the plaintiff, divide one by three and enter 33.33% in the plaintiff's column, then divide two by three and enter 66.67% in the defendant's column on line 5b.) 
7. Line 5(c). Multiply line 4 by line 5b for each parent and enter the results on line 5c.
8. Line 6(a). Multiple defendant's line 5c by plaintiff's line 3 (plaintiff's percentage share of income) and enter the result in the column for plaintiff.
9. Line 6(b). Multiply plaintiff's line 5c by defendant's line 3 and enter the result.
10. Line 7a through 7c. Enter the amount of work-related child are costs, health insurance premiums for the child(ren), and extraordinary child-related expenses that are paid by either parent under the column for that parent. 
11. Line 7d. Enter the sum of lines 5a through 5c for each parent, and in the third column (Combined) enter the total expenses paid by both parents.
12. Line 8. Multiply line 7d (Combined) by line 3 for each parent and enter the result under the column for that parent. 
13. Line 9. Subtract line 8 from line 7d for each parent and enter the result (if negative, enter zero).
14. Line 10. Subtract line 9 from line 6a or 6b for each parent and enter the result under the appropriate column.  In some cases, the result may be a negative number. If the result is negative, enter it as a negative number on line 10, not as a positive number or as a zero. 
15. Line 11. If plaintiff's line 10 is greater than the defendant's line 10, enter the difference between these two amounts on line 11 under plaintiff's column and leave defendant's column blank.  If defendant's line 10 is greater than plaintiff's line 10, enter the difference between these two amounts on line 11 under defendant's column and leave plaintiff's column blank.  [Note that if either of the numbers on line 10 is a negative number, you must change the signs with you subtract. For example, $100 minus negative $50 equals $150.]

N.C. Admin. Office of the Courts, N.C. Child Support Guidelines, AOC-A-162, Instructions for Worksheet C (1998).