Written for Mexico. This analysis applies to Mexican federal tax law — ISR (income tax), IVA (VAT) and SAT rules — and cites Mexican statutes. Amounts are in Mexican pesos (MXN).
At year-end almost no one knows, precisely, how much ISR was withheld from them — you trust that the employer "already calculated it right." But whether your annual return comes out with a refund, a balance due or at zero depends on that number. The good news: the SAT has a free tool that shows you exactly what your employer reported in your name, receipt by receipt. It's called the payroll-receipt viewer, and you should review it before every annual return.
What the worker payroll viewer is and what it's for
Every time you get paid, your employer is required to issue a payroll CFDI (a stamped receipt) and to withhold your ISR under the mechanics of art. 96 LISR. The worker payroll viewer concentrates all those receipts in one place: you log in with your RFC and Contraseña and see, by fiscal year, the total wages, the ISR withheld from you, the employment subsidy applied, and the breakdown of taxable and exempt earnings. It's not your own estimate or your accountant's calculation — it's what the employer actually stamped with the SAT, which is also the information the authority uses to pre-load your annual return. The direct access is in our resource center.
How to log in and what to review, step by step
You log in to the worker payroll viewer on the SAT portal with your RFC and Contraseña (you don't need e.firma, the SAT's digital signature). You pick the fiscal year and review three things. One: that all the periods you worked are there — if you changed jobs or were paid a Christmas bonus (aguinaldo) or final pay (finiquito), each event should have been stamped. Two: that the year's ISR withheld matches what you added up from your receipts. Three: that the exempt earnings (aguinaldo up to 30 UMA — the daily reference unit —, vacation premium, savings fund, etc.) are correctly classified, because a misapplied exemption inflates your base and your tax. If something doesn't appear or doesn't tie out, you already have the hard data to take it up with your employer or correct it in your annual return.
The differences you should look for — and what they mean
A period or an employer is missing. If you worked somewhere and its receipts don't appear, that employer didn't stamp (or stamped incorrectly) — and that income might not be in your pre-loaded annual return, which sooner or later produces a discrepancy. The ISR withheld is lower than it should be. With two simultaneous jobs this is normal: each employer withholds as if you were its only worker, and when you add up your income you move up a bracket in the rate schedule — hence the surprise balance due that catches so many off guard, which we explain in why your annual return comes out owing. Exempt earnings inflated or wrongly placed. Careful: if an employer classified as exempt something that wasn't, the correction falls to you on the annual return. The viewer doesn't correct — it shows you where to look.
Why this matters before your annual return
An employee's annual return is no longer built from scratch: the SAT pre-loads it with these same payroll CFDI. If the employer's data is wrong, your annual return is born wrong — and accepting it without review means inheriting the error. Reviewing the viewer before filing gives you three plays: demand that your employer correct a wrong stamping, capture your personal deductions properly to lower the result, and file with the peace of mind that what you report matches what the SAT already has. Five minutes of review against weeks of clarifications if something blows up later.
Frequently asked questions
Do I need e.firma or is the Contraseña (password) enough?
Your RFC and SAT Contraseña (password) are enough to log in to the worker payroll viewer; it doesn't require e.firma. If you don't have it or forgot it, it's generated or renewed online. It's an informational query: you file nothing and sign nothing, you just review what your employer stamped.
How far back does the viewer's information go?
The viewer concentrates payroll receipts stamped since the payroll CFDI became mandatory, and shows the recent fiscal years separately. For a current year you'll see whatever has been stamped to date; it's worth reviewing near year-end and again before filing the annual return.
What do I do if a receipt is missing or the figures don't tie out?
First, take it up with your employer: they're the one who stamps, and they can reissue or correct the CFDI. If the ISR withheld doesn't match, keep your receipts as backup and adjust in your annual return with the real figures. If the employer doesn't correct it and the amount is significant, it's an issue worth reviewing carefully before filing.
Is the viewer the same as my annual return?
No. The viewer is the source: it shows you what was stamped. The annual return is where that figure turns into a refund or an amount owed, adding other income and subtracting your personal deductions. The SAT pre-loads the annual return with the viewer's information, but you're still responsible for the result being correct.
Found differences in what was withheld from you?
An employer that over-withheld, two jobs that left you owing, misclassified earnings: when the viewer exposes a difference, the question is what to correct and how, without opening a front with the SAT or with your employer. We review it with your numbers and tell you the cleanest path.