Washington Child Support: How Much & How Long Will I Pay?

Posted on March 11, 2018.

If you’re having trouble understanding child support in Washington you’ve come to the right place. Once you understand the basics, it is fairly easy to understand and one of the most transparent pieces of the divorce process.

In short, your child support payments are determined by a mathematical formula. You can use Washington’s child support economic table to find the total support obligation. Then calculate your share based on the proportion of income you contribute compared to your spouse. Typically payments will last until a child reaches age 18 or graduates from high school.

This article will show you how to calculate support on your own, discuss the specifics of the calculation and explain the factors that determine the length of payment


  • How to Calculate your Child Support
  • How to Calculate Duration
  • Typical Cut Off: Only Child
  • Typical Cut Off: Multiple Children
  • Support Into College
  • Special Needs
Child Support

Calculating Washington Child Support

Follow the four steps below to determine your child support amount.

Step 1

First, calculate your gross monthly income. Then determine your spouse’s gross monthly income. Gross monthly income is the amount you make per month before taxes and other deductions.

Typically this is fairly straightforward. Although, things can get a bit complicated when spouses have second jobs or other secondary income streams.

If you were able to calculate gross monthly income without issues you can skip to step 2. If you’re not sure what to include, I’ll provide some examples below where other spouse’s get stuck and show you less common sources of income that can be excluded.

Since higher income leads to larger payments, couples can get stuck at this point. Take the couple Jesse and James.

Jesse doesn’t believe her side job with Trocket Industries should be included, since she already works 40+ hours a week as a zoologist. At the same time, James thinks his trading card business on eBay should be omitted, since he started it with a collection that he owned before marriage.

Disagreements like these aren’t uncommon. If you also have a complicated income stream, refer to the list below, which specifies what to include or omit as an income source. This will ensure you are working with proper and complete financial information.

Included Income

  • Salaries, Wages, Commissions, Bonuses
  • Deferred compensation
  • Overtime* (see omissions)
  • Contract-related benefits
  • Income from second jobs* (see omissions)
  • Dividends & Interest
  • Trust income
  • Severance pay
  • Annuities, Capital gains, Pension retirement benefits
  • Workers’ compensation, Unemployment benefits, Disability insurance benefits
  • Spousal support received
  • Social security benefits
  • Income from self employment, rent, royalties, contract, proprietorship of a business, or joint ownership of a partnership or closely held corporation
  • Social security benefits paid to a child because of a parent’s disability
  • Benefits from unused sick leave for later use

Omitted Income

  • Income of a new spouse or new domestic partner or income of other adults in the household
  • Child support received from other relationships
  • Gifts and prizes
  • Temporary assistance for needy families
  • Supplemental security income
  • Aged, blind, or disabled assistance benefits
  • Pregnant women assistance benefits
  • Food stamps
  • Overtime* or income from second jobs* beyond 40 hours per week averaged over a 12-month period worked to provide for a current family’s needs, to retire past relationship debts, or to retire child support debt, when the court finds the income will cease when the party has paid off his or her debts

It is often most efficient to make a list of your income sources and then check it against the omission list. Anything not listed will be included. Just make sure not to forget obscure income types like benefits from unused sick leave or one-time income sources like bonuses or sales commissions.

Imputed Income

Also, be aware of a common exception, imputed income. This occurs when a spouse is not working even though they are capable. It can also come up when a spouse works, but only part time or in a role they are overqualified for.

For example, say James is a graduate of the University of Washington with a degree in business administration. Seven months ago he was laid off from Microsoft, but hasn’t found a job and pays his bills by driving for Uber and selling collectible trading cards. James is capable of working full time. Would the court use his recent earnings to calculate his child support contribution or his earning potential?

In this situation, the court will most likely calculate James’ income based on what he earned at Microsoft. Because he is voluntarily under-employed a court can use his previous earnings as a benchmark. Similarly, if James weren’t working at all, the court would use his past earnings to determine income.

Step 2

Once gross income is determined subtract any deductions. This will give you what is called net income. Common deductions include federal income taxes, social security, and mandatory union dues. Once this is done you will have the net income for both parents and you can determine the amount of child support with the help of the economic table.

Tip: The hardest part for most people is getting the taxes right. Use an online tax calculator to make sure yours are correct.

Step 3

Find the amount owed for each child. The child support economic table provides a support amount per child for families with 1 to 5 children and with monthly net incomes between $1,000 and $12,000. This does not cover all scenarios, for example, families with more than five children, but it can be still be used to establish a baseline.

Go to the section of the chart that coincides to your combined net monthly income. To the right, you’ll find the total child support amount per child, which is based on the number of children in your family. Below is a portion of the chart for reference.

Step 4

Determine the total and then your share of the total. The dollar amounts in the above chart are per child, so you’ll need to multiply the value shown by the amount of children.

For example, Jesse and James have two children, ages 13 and 5, and a combined net income of $1900. Based on the economic table, the total child support obligation is $634 per month ($317 for the 13 year old and $317 for the 5 year old).

Proportional Share – Custodial Parent

The proportional share of each parent is the percentage each parent contributes to the combined net income. In the above example James adds $800 per month and Jesse adds $1100. Therefore, James’ share is 42.1%, while Jesse’s share is 57.9%. Translated into dollars:

James = 634 * 42.1% = $266.91

Jesse = 634 * 57.9% = $367.09

Assuming that James is the custodial parent, meaning the children live with James the majority of the time, Jesse will transfer $367.09 to James each month.

Proportional Share – Joint Custody

Alternatively, if the children spend equal time with both parents then half the difference between the two amounts will be transferred to the parent with the smaller share. Using the same numbers:

James = 266.91 * ½ = $133.46

Jesse = 367.09 * ½ = $183.55

Jesse would transfer $50.09 (i.e. 183.55 – 133.46) to James each month.

Other Considerations

The economic table does not include support for health care, day care, or other specific expenses like tuition. These other expenses are generally added to the obligation and then divided based on each parent’s proportional share of income. Sometimes parents agree to split additional child care costs evenly instead of proportionally.

Also, while we covered common scenarios, the calculations made with the child support economic table are not set in stone. A court will consider additional factors and award a different amount in the right circumstances.

Child support Washington

How long will payments last?

In most cases child support ends at the later of these two events, a child turns 18 or graduates from high school. However, there are situations, which will lead to child support lasting longer. Below are a few examples to help you determine the duration of support.

Typical Cut-Off: Only Child

John is a senior in high school. He just turned 18 in March and has three months to go before graduation. John’s father claims that he no longer is responsible for child support since John is an adult. John lives with his mother, Samantha, who supports him. Samantha asks:

  1. Does child support actually end even though John is still a high school student?
  2. If John’s father won’t pay, can she do anything for help with expenses while he’s still in school?

First, Samantha should check the divorce decree. It may specify that payments end when John graduates from high school. If the divorce decree doesn’t include an end date, technically child support ends on John’s 18th birthday. However, since John is still in school and supported by Samantha, she can file a motion in court asking to extend payments until graduation.

Typical Cut-Off: Multiple Children

Frank divorced three years ago. He has two children, Gertrude and Tabitha. At the time of the divorce Gertrude was 15 and Tabitha 12. Gertrude just celebrated her 18th birthday on February 27th. She’s a senior in high school and graduates in June.

Frank currently pays $1050 a month. He wants to know:

  1. Can he stop paying for Gertrude now that she’s 18?
  2. Is the amount reduced by half now that only one child is under 18? If not, how can he determine the new amount?
  3. Does he need to take any official steps to alter the amount?

One, Frank should check the divorce decree to see if it specifies any changes that take place once Gertrude turns 18. If the documents do not address the issue, he can’t just stop paying. He will need to take legal steps to decrease the amount.

Two, the amount is not simply decreased by half. He can follow the steps outlined above to determine the new amount that he should pay for just Tabitha. He should know that net income will be based on the current financial situation, not the financial values used during the divorce three years prior.

Three, he should file a motion with the court to decrease the amount now that Tabitha is the only minor child remaining. He’ll have the best chance of success if he waits until Gertrude graduates from high school. If he asks before she graduates, he will likely be denied.

Support into College

Steve and Linda divorced last year. They have a 17 year old daughter, Maria, who’s been accepted at Washington State University. Linda just filed a motion in court asking that Steve help support Maria with the cost of her college education.

Can a court order Steve to pay for postsecondary school even though Maria will be 18 and a high school graduate?

Parental support through college is not mandatory. It is awarded depending on a list of factors. A parent can ask the court to order both parents to contribute to postsecondary school anytime before a child’s 18th birthday.

A court will consider:
a. Age of the child
b. Child’s needs
c. Expectations of the parents for their children when they were together
d. Child’s prospects, desires, aptitudes, abilities or disabilities
e. Nature of postsecondary education sought
f. Parents’ current and future resources, level of education, and standard of living
g. The amount and type of support that the child would have been afforded if the parents stayed together.

Educational options are not limited to just four year universities. Professional training, community colleges, vocational training and other schooling designed to better future job prospects can be considered. Payments generally go directly to the institution to cover tuition and board. Otherwise, payments can be made to the child directly.

Typically the court will not require postsecondary support past age 23. Also, the child must remain in good academic standing or else the support can be revoked.

Special needs

If a child has special needs child support will likely continue past age 18. Typically this is addressed in the original child support order, but in the instance where a condition occurred after the original order parents can ask for support after 18. Support should last until the child is capable of supporting themselves.

For example, if a child has a severe disability and will need continued assistance after high school, his parents likely planned for child support after 18 in the original court order. Alternatively, if a child suffers a major injury from a car accident and is unable to work full time or continue schooling due to the injury, parents may need to contribute child support past 18. Child support can continue indefinitely if a child is never able to fully support themselves.


Hopefully, this post helps you value child support and understand how long payments will last. If you have further questions or would like help with your own child support calculations, visit Truce Law website or call us at 206.409.4086 or send us an email.  


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