Typical path: Settings → Pay Details → Federal Taxes. Menu names vary by employer, so each step below tells you what to search for if a label differs.
Open Settings, go to Pay Details, edit the Federal Taxes section, enter only the steps from your W-4 plan, and save. The change usually takes effect within 1 to 2 pay periods. Verify it on your next paystub.
Use your employee login. If your company uses single sign-on, complete that step first, then open your Gusto profile.
Select Settings (sometimes under your profile menu). This holds your personal, job, and pay configuration.
Choose Pay Details (sometimes labeled Job & Pay or Compensation). This page shows your pay rate, pay schedule, and tax sections.
Select Federal Taxes to open your federal W-4 elections. Review the current values first so you only change what your plan requires.
Type your Step 4(c) extra-withholding amount (per paycheck) or Step 4(b) deduction figure (yearly). Check Box 2(c) only if your plan calls for it on this job.
Save the change. Gusto typically shows a confirmation — keep a screenshot. Check your next paystub FIT line; if nothing changed after two pay periods, ask your admin whether the update was received.
Run the free check, then unlock your per-paycheck Step 4(c) amount.