Understanding your W-4 tax form
The W-4 form tells employers how much tax to withhold from your paycheck. This article explains what the W-4 is and how to submit it when you need to update your tax withholdings.
What is a W-4 form?
A W-4 form is a legal tax document that:
- Determines how much tax comes out of your paycheck
- Helps you avoid owing a lot at tax time
- Needs to be updated when your tax situation changes
- Is required for all W-2 employees
When you need to fill out a W-4
You'll need to complete a W-4 form:
- When you first become a W-2 employee with Instawork
- If you want to change your tax withholding
- When your personal or financial situation changes (marriage, new child, second job)
How to fill out your W-4
1. Access the W-4 form here: W4 2025.pdf
2. Complete all required fields:
- Personal information (name, address, Social Security Number)
- Filing status (single, married, head of household)
- Multiple jobs or working spouse information (if applicable)
- Dependents (if applicable)
- Other adjustments (if applicable)
3. Submit your completed form here: W4 Submission Form
Please allow 1 -3 business days for processing.
Requirements for a valid W-4
Your W-4 form must be filled out correctly to be valid. A W-4 is considered invalid if it has:
- Blank or incomplete required fields
- Crossed-out, altered, or illegible information
- Missing signature
- Conflicting or unclear withholding elections (like multiple boxes checked in Step 2)
If your form is invalid, you may need to submit a new one, which could delay your payment processing.
Important things to know
- Your W-4 remains in effect until you submit a new one
- You can update your W-4 at any time if your tax situation changes
- The more accurate your W-4, the more accurate your tax withholding will be