Contact
Get in touch.
Line 4C.com is operated by Red Goggles LLC. We read every message — especially corrections. When the tool touches your paycheck, accuracy matters to us.
The fastest way to reach us is email: [email protected]. It reaches the team that maintains this site.
What we can help with
- Corrections. If a figure looks wrong or out of date — a Table 1 value, a pay-period count, or the tax year the grid reflects — tell us and cite a source if you have one. We verify against the current-year Form W-4 and update.
- Questions about the tool. How an input is used, what the estimate assumes, or how the mid-year proration works.
- Feedback. Anything confusing, broken, or missing.
What we can’t do
We can’t give personalized tax advice, prepare your return, or tell you your exact tax outcome — those depend on your full financial picture. For those, use the IRS Tax Withholding Estimator or a qualified tax professional (a CPA or enrolled agent). See our disclaimer.
Privacy
We don’t collect your calculator inputs, and we don’t need your personal information to answer a question. For details, see our privacy page.