Step #1:
Log in to your Checkbook.io account.
Step #2:
Go to "Settings" on the bottom left-hand side of the page.
Step #3:
When in Settings, click on the "Accounts and Cards" tab.
Step #4:
Under accounts, ensure you're in the Bank Accounts tab. Click on "Add Account" to add a bank and follow the next step
Step #5:
You may add your bank account through Instant Verification.
If Instant Verification does not work for you, please choose Manual Verification.
Step #6:
Add your Bank Account.
Step #7:
Follow the prompts displayed to go through the account verification process.
NOTE: Please ensure the "Default" toggle is on for the desired bank account.