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).
Your pension does not depend on how much you earned "more or less," nor on how many years you worked "roughly": it depends on an exact number that the IMSS (Mexico's social security institute) keeps for you from your first job — your weeks of contribution — and on that record being correct. The statement that proves it is available free, online, in five minutes (direct link in the Resource Center) — and reviewing it every year is one of the most profitable financial habits there is, because errors are cheap to fix today and ruinously expensive at 64.
What counts and why it decides everything
Each week with an employment relationship registered with the IMSS adds one week of contribution — with any employer, regardless of job changes (the NSS is unique and the record follows it). The number governs two worlds: under Ley 73 (the 1973 law — if you contributed before July 1997) you need 500 weeks and your pension is calculated on the average salary of your last 250 — the generous regime, where end-of-career strategies like Modalidad 40 can multiply the pension. Under Ley 97 (the 1997 law — Afore, the individual retirement-account system), the weeks requirement for a guaranteed pension keeps rising under the 2020 reform: 875 in 2026, climbing 25 per year up to 1,000 in 2031 (high confidence in the trajectory; the exact year of your retirement defines your number). Intermediate doors also open: work-injury benefits, disability, and even the Infonavit housing loan awards points based on your record.
How to pull the statement — and what to hunt for in it
In the IMSS online weeks-of-contribution service: CURP, NSS and an email; you download the report on the spot, with your total and the breakdown by employer and period. The smart read looks for three faults: gaps (periods you worked that don't appear — employers who never registered you or filed a "paper-only" termination), registered salaries lower than the real ones (this silently robs you of pension and credit — under Ley 73, the salary of your last years is worth gold), and inconsistent personal data (identical-name mix-ups, two NSS numbers — these are merged at your IMSS Subdelegación office, and doing it before any pension procedure avoids months of limbo). Weeks corrections are filed with the IMSS with your employment evidence from the period: pay stubs, contracts, bank statements — another reason for a permanent personal archive.
Are you 5–15 years from retirement — or do you have workers who trust that their record is right?
Pension strategy is played in advance: verifying the applicable regime (Ley 73 vs. 97), auditing the record, and where appropriate designing Modalidad 40 or other optimization routes — decisions where months of timing are worth double pensions. And on the employer side: registering your people correctly is not just compliance; it's the silent liability that lawsuits over recognition of rights turn into million-peso bills decades later.
Frequently asked questions
I worked for years in the nineties and they don't show up — are they lost?
They aren't lost — but old records are sometimes not correctly linked to your NSS. You claim them through the weeks correction (aclaración de semanas) with the IMSS, providing evidence of the employment relationship from that period. Start by checking that you don't have a second NSS where those weeks were orphaned: it's the most common cause.
Can I 'buy' weeks if I'm short?
Buy, no — but voluntary continuation (Modalidad 40) lets you keep contributing on your own after leaving formal employment, at the salary you register (capped), adding weeks and raising your average salary if you're under Ley 73. It's the most powerful pension-optimization tool in the system — and the one that most demands fine-tuned design of dates and amounts.
I stopped contributing years ago — do my weeks expire?
Weeks aren't erased, but under Ley 73 there is 'conservación de derechos' (retention of rights): after a certain time without contributing, to retire you need to reactivate by contributing for a prior period (re-entering the scheme). If you've been out for years and you're under Ley 73, the reactivation route is exactly the kind of play you plan on a calendar.
Let's talk about your case
The first step is always the same: an honest diagnostic of where you stand. Write to us on WhatsApp or call — a reply the same business day.