Basic Calculation: DETERMINE WHICH FORMULA APPLIES BY CHECKING THE BOXES BELOW: QUESTION A: Will child support be paid for childrenof the marriage? This formula takes into consideration the needs of the child(ren) and the ability of the parents to meet those needs.Confused about Clark County child support calculations? By Thomas C. Montoya, Family Lawyer. 1. Husband and Wife were married for 13 years. The results obtained are only as accurate as the information provided in the calculator. 2009) (in a 14-year marriage where. Washington law does not give specific guidelines for calculating spousal support as it does with child support determinations. Modification is a change of the provisions in a support order based upon a significant change of circumstance. The court orders this type of award when one spouse cannot work or support themselves due to age or disability.