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Make an online payment.

Explaining the online payment fields

Account Number

This is the account number in the King County Sewage Treatment Capacity Charge billing system for the property being charged. You can find the number for your account in the upper and center portion of the paper invoice you received in the mail.

Invoice displaying account number

Site Number

This is the site number that identifies you and your billing address for the property being charged. You can find your Site Number in the lower center portion of the paper invoice you received in the mail.

Invoice displaying site number


This is the property address for this account.

Invoice displaying address

Invoice Number The number for the invoice mailed to you.
Invoice Date

This is the date of the most current open invoice. Your invoices will be dated every three or six months.

It depends on when the property was connected to sewer. For properties connected prior to 2007, the invoices are dated every six months. If the connection was in 2007 or after, invoices are dated every three months.

Billing Period The invoice covers the previous months listed.
Remaining Balance

The total capacity charge amount remaining for this property.

It consists of all outstanding invoices including Past Due Balance, Invoice Amount For This Billing Period, and future invoices for the remaining 15-year billing period.

Early Payoff Amount

The amount to pay if you wish to pay your account off in full with one lump-sum payment.

The discount rate is revised to closely reflect economic trends. The capacity charge is not like a mortgage, and there is no benefit in making extra payments unless all remaining invoices are paid.

If an extra payment is included, it will be applied to future invoices and your next invoice may show a zero balance due.

Past Due Balance

The total amount from unpaid previous invoices. Past Due invoices are subject to a 10% late fee and interest in accordance with King County Code 28.84.050.

Invoice Amount

The amount billed for the dates listed. If the bill covers three months, the invoice will be for the monthly rate times three.

Amount Due Now

The total of the Past Due Balance and the Invoice Amount For This Billing Period. It is the amount that needs to be paid to be current on the account. Interest and late fees may be added if there is a past due amount.

Due  Date The date the payment is due to avoid late charges or to take advantage of the discounted early pay-off amount. It is 30 days after the Invoice Date.
Make Selection Pay Amount Due Now: Select this option to pay the amount due at this time. The dollar amount will be entered for you automatically.
Pay Early Discounted Amount: Select this option to pay the discounted early payoff amount. The dollar amount will be entered for you automatically.
Pay Other Amount: Select this option to pay some other amount. Enter the amount you want to pay into the Payment Amount field.
Payment Amount

The amount you are paying at this time. If you pay less than the amount due at this time, your account may incur late charges. Please call customer service at 206-296-1450 and make arrangements if you cannot pay the full amount due.

Making payments

The payment methods accepted for paying your sewage treatment capacity charge are limited to MasterCard, Visa, American Express, Discover and e-check.

E-checks are an electronic version of a physical check. When you make your online payment, you authorize the bank to electronically withdraw funds from your checking or savings account for the amount of your payment.

King County accepts personal checks and business checks to make your capacity charge payment.

In order to create an e-check, you will be asked for specific numbers that appear at the bottom of your physical check.

  • The Routing Transit Number (RTN) is the 9-digit number that identifies your bank. It is the first group of numbers at the bottom of your check.
  • The Account Number appears as the second group of numbers to the right of the RTN.

Be careful not to include the check number, which is the third group of numbers located to the right of the Account Number.


Note: If you enter the wrong account number in error and your electronic check does not successfully clear your bank account, you will be assessed a NSF charge and any applicable delinquency charges by the County.

Effective July 1, 2021, a service fee of 2.35% ($2.00 minimum) will be assessed to all credit card transactions or $1.00 flat-fee for eChecks.

Customers participating in the Capacity Charge Low-Income Housing Program will not be charged a service fee. To learn more about this program, please view this fact sheet .

Your credit card or bank account will be charged immediately upon payment, but it will not be applied to your capacity charge account for 1 to 2 business days.

You may cancel out of the payment process at any time before you have submitted your payment by clicking the "Cancel" button at the bottom of the form.

To prevent accidental cancellations, you will be directed to a page where you will be required to click a button indicating that you wish to confirm the cancellation request. Once you have confirmed that you wish to cancel, all the data you have entered will be discarded and you will be taken to the capacity charge payment homepage.


When a payment error occurs, you will be returned to the page where the payment data was originally entered. A table at the top of the page will display the error with two fields: a message field and a recommended action field.

The message field describes the error that occurred during the processing of the payment.

The recommended action field describes the action likely to resolve the issue.

To re-try payment, follow the recommended action in the error box and click "Continue" after you’ve made the corrections.

You will be required to confirm your information again before the payment is submitted to the processor.

Please note: the payment system is down for scheduled maintenance every 3rd Sunday of the month, 6:00 a.m. - at 11:30 a.m. PST, and every 3rd and 4th Thursday of the month, 5:00 p.m. - 7:00 p.m. PST.

On occasion, the system requires maintenance outside this weekly time period.

Please revisit the site at a later time to make your payment, or make a payment by sending a check in the mail.

Contact Us

Phone: 206-296-1450

Fax: 206-263-6073