Most balance-due surprises in April were visible in January. A new job, a raise, a spouse going back to work, a side business: each changes what should be withheld, and few people update their W-4. A paycheck checkup campaign gives clients a simple way to spot the gap, and gives your firm a reason to talk to them in a quiet month.
Why paychecks, and why January
The first paycheck of the year looks different: new benefit elections, a raise, and for high earners the Social Security wage base resetting. Clients notice and wonder. If they check now, a W-4 change spreads the fix over eleven months. If they wait until April, the fix is a check to the IRS, and possibly an underpayment penalty.
Who to target
| Group | Why they’re at risk | Calculator |
|---|---|---|
| Two-earner couples | Each employer withholds as if it’s the only job | Take-home pay |
| New job or raise | Old W-4, new income | Take-home pay |
| Hourly with overtime | Irregular pay, new overtime deduction | Hourly paycheck |
| Side income | No withholding on 1099 income | Self-employment tax |
| High earners | Additional Medicare Tax thresholds differ for couples | Take-home pay |
The January email
New year, new paycheck. If your pay, job or family changed in 2025, check what your 2026 paycheck should be after federal tax: [link]. If the number surprises you, reply and we’ll review your W-4 before it becomes an April problem.
Keep it to three sentences. Link to a page on your site with your own two-paragraph introduction and the calculator.
What a request tells you
A paycheck request includes salary, pay frequency, filing status and pre-tax deductions. From that you can see:
- whether the client is near the Social Security wage base;
- whether pre-tax deductions are being used well;
- whether a two-earner household is likely under-withheld.
Your reply can then offer a W-4 review, and for prospects, a quote for this year’s return.
The mid-year rerun
Run a shorter version in June or July, after raises and bonuses. Add the net to gross calculator for clients negotiating pay and the contribution effect calculator for those who want to save more without feeling it.
Keep it accurate
The calculators estimate federal income tax and FICA using 2026 figures; they leave out state and local tax and credits like the child tax credit. Say so on the page. When you recommend a W-4 change, that’s written advice, so base it on the facts (both spouses’ pay, credits, other income), not only the calculator inputs.
Measure
Count requests, W-4 reviews completed, and the April balance-due surprises among clients who took part versus those who didn’t. That last comparison is the best argument for running the campaign again.
