Not tax advice. Computation tools only. Have a professional check your work before filing.

Use this skill with your AI agent

View on GitHub

Paste this skill into your AI agent's context, or save the file to your project. Works with any AI agent that reads markdown.

mx-imss.md394 lines16.6 KB
v20Mexico
Not yet verified by an accountantContact accountant
1---
2name: mx-imss
3description: >
4 Use this skill whenever asked about Mexican IMSS social security for self-employed individuals. Trigger on phrases like "IMSS", "seguro social Mexico", "regimen voluntario", "incorporacion voluntaria", "IMSS freelancer", "aseguramiento voluntario", "Modalidad 40", or any question about voluntary IMSS enrollment, contribution calculation, or benefits for self-employed persons in Mexico. Covers voluntary inscription (Modalidad 40, regimen voluntario), contribution bases, health/maternity/retirement/disability benefits, and tax deductibility. ALWAYS read this skill before touching any Mexican IMSS work.
5version: 2.0
6jurisdiction: MX
7tax_year: 2025
8category: international
9depends_on:
10 - income-tax-workflow-base
11---
12 
13# Mexico IMSS Self-Employed Skill v2.0
14 
15---
16 
17## Section 1 -- Quick Reference
18 
19| Field | Value |
20|---|---|
21| Country | Mexico |
22| Tax/Contribution | IMSS Social Security (voluntary self-employed) |
23| Currency | MXN only |
24| Primary legislation | Ley del Seguro Social (LSS) |
25| Supporting legislation | Reglamento de la LSS en materia de Afiliacion; Ley del INFONAVIT; Ley del ISR Art. 151 |
26| Authority | Instituto Mexicano del Seguro Social (IMSS) |
27| Portal | IMSS Digital (imss.gob.mx) |
28| Filing deadline | Monthly contributions; enrolment at any time |
29| Contributor | Open Accountants Community |
30| Validated by | Pending -- requires sign-off by a Mexican contador publico or social security specialist |
31| Skill version | 2.0 |
32 
33### UMA Reference Values (2025 -- verify with INEGI)
34 
35| Item | Approximate Value |
36|---|---|
37| Daily UMA | MXN 113.14 |
38| Monthly UMA | MXN 3,439.46 |
39| Annual UMA | MXN 41,273.52 |
40 
41### IMSS Five Branches of Insurance
42 
43| Branch | Coverage |
44|---|---|
45| Enfermedades y Maternidad | Medical care, prescriptions, maternity leave |
46| Invalidez y Vida | Disability pension, death benefits |
47| Retiro, Cesantia y Vejez | Old-age pension, unemployment in advanced age |
48| Riesgos de Trabajo | Work accidents and occupational diseases |
49| Guarderias y Prestaciones Sociales | Daycare, social services |
50 
51### Voluntary Enrolment Options
52 
53| Option | Who | Coverage | Key Detail |
54|---|---|---|---|
55| IVRO (Art. 13) | Self-employed, freelancers | All 5 branches | Total contribution approx. 31-33% of chosen base |
56| Seguro de Salud para la Familia (Art. 240) | Any non-covered person | Health only | Fixed annual cost by age bracket; NO pension |
57| Modalidad 40 (Art. 218) | Former employees with 52+ prior weeks | Pension only (Invalidez y Vida + Retiro) | Total approx. 10.075% of chosen base; max 25 UMA |
58 
59### Conservative Defaults
60 
61| Ambiguity | Default |
62|---|---|
63| Employment status unknown | STOP -- do not proceed |
64| Prior contribution weeks unknown | Assume ineligible for Modalidad 40 until confirmed |
65| Desired salary base unknown | Use 1 UMA (minimum) for estimates |
66| UMA value unconfirmed | Direct client to INEGI for current value |
67 
68---
69 
70## Section 2 -- Required Inputs and Refusal Catalogue
71 
72### Required Inputs
73 
74**Minimum viable:** Confirmation of self-employed status, CURP, RFC, and whether currently enrolled in any IMSS regime.
75 
76**Recommended:** Prior IMSS contribution history (semanas cotizadas), desired salary base for contributions, family members to cover.
77 
78**Ideal:** Full contribution statement from IMSS, prior year ISR return, INFONAVIT status.
79 
80### Refusal Catalogue
81 
82**R-MX-1 -- Salaried employees.** "If the client is a salaried employee, the EMPLOYER handles IMSS. This skill covers self-employed/voluntary enrolment only. Stop."
83 
84**R-MX-2 -- Employer-employee IMSS disputes.** "Disputes between employers and IMSS regarding contributions or registrations are outside this skill scope. Escalate to a specialist."
85 
86**R-MX-3 -- Disability claims.** "IMSS disability benefit claims require medical and legal evaluation. Escalate."
87 
88**R-MX-4 -- INFONAVIT complex cases.** "INFONAVIT credit interaction with voluntary IMSS is outside this skill scope. Escalate."
89 
90---
91 
92## Section 3 -- Transaction Pattern Library
93 
94This is the deterministic pre-classifier for bank statement lines related to IMSS.
95 
96### 3.1 IMSS Payment Patterns (Debits)
97 
98| Pattern | Category | Treatment | Notes |
99|---|---|---|---|
100| IMSS CUOTA OBRERO PATRONAL / IMSS PAGO | IMSS contribution | EXCLUDE from business expenses | Personal social security -- ISR deduction (Art. 151) |
101| IMSS REGIMEN VOLUNTARIO / IMSS IVRO | IVRO contribution | EXCLUDE from business expenses | Personal deduction for ISR |
102| IMSS MODALIDAD 40 / IMSS MOD 40 | Modalidad 40 payment | EXCLUDE from business expenses | Personal deduction for ISR |
103| IMSS SEGURO SALUD FAMILIA / IMSS SSF | Family health insurance | EXCLUDE from business expenses | Medical expense deduction (limited) |
104| INFONAVIT / INFONAVIT PAGO | Housing contribution | EXCLUDE | Not IMSS; separate programme |
105 
106### 3.2 IMSS Benefit Patterns (Credits)
107 
108| Pattern | Category | Treatment | Notes |
109|---|---|---|---|
110| IMSS PENSION / PENSION IMSS | Pension income | Taxable income | Report as pension income on ISR return |
111| IMSS INCAPACIDAD / SUBSIDIO IMSS | Disability/sickness benefit | Verify tax treatment | May be exempt up to certain amounts |
112| IMSS REEMBOLSO | IMSS refund | EXCLUDE | Not income |
113 
114---
115 
116## Section 4 -- Worked Examples
117 
118### Example 1 -- IVRO at Minimum Base (1 UMA)
119 
120**Input:** Self-employed designer, no prior IMSS coverage, wants minimum coverage for self and family.
121 
122**Reasoning:**
123IVRO at 1 UMA daily (approx. MXN 113.14/day). Monthly base approx. MXN 3,439.46. Self-employed pays both employer and employee shares. Total rate approx. 31% of base. Monthly cost approx. MXN 1,066. Covers all 5 branches including health for family.
124 
125**Classification:** IVRO monthly contribution MXN 1,066. Deductible for ISR purposes under Art. 151.
126 
127### Example 2 -- Modalidad 40 at Moderate Base
128 
129**Input:** Former employee with 200 weeks prior contributions. Left employment 2 years ago. Chose base of 10 UMA daily.
130 
131**Reasoning:**
132Eligible for Modalidad 40 (has 52+ weeks, within 5-year window). Daily base: approx. MXN 1,131.40. Monthly base: approx. MXN 34,394.60. Rate: approx. 10.075%. Monthly cost: approx. MXN 3,465. Covers pension only -- NO health coverage.
133 
134**Classification:** Modalidad 40 contribution MXN 3,465/month. Deductible for ISR. Client needs separate health coverage.
135 
136### Example 3 -- Seguro de Salud para la Familia
137 
138**Input:** Family of 4: 2 adults (age 35, 33), 2 children (age 8, 5). No current IMSS coverage.
139 
140**Reasoning:**
141Annual cost per person based on age brackets. Adults (19-39): approx. 7.5% of annual UMA each. Children (under 19): approx. 5.9% of annual UMA each. Total annual: approx. MXN 11,061. Health coverage only; no pension.
142 
143**Classification:** Annual family health premium MXN 11,061. Deductible as medical expense (limited).
144 
145### Example 4 -- Modalidad 40 at Maximum Base
146 
147**Input:** High earner wanting maximum pension. 500 weeks prior contributions. Chose 25 UMA daily.
148 
149**Reasoning:**
150Maximum Modalidad 40 base: 25 UMA daily = approx. MXN 2,828.50/day = approx. MXN 85,987/month. Monthly cost: approx. 10.075% = MXN 8,663. Maximum pension accumulation strategy.
151 
152**Classification:** Modalidad 40 contribution MXN 8,663/month. Maximum pension strategy. Flag for reviewer to assess long-term pension impact.
153 
154---
155 
156## Section 5 -- Tier 1 Rules (When Data Is Clear)
157 
158### 5.1 IVRO Contribution Rates (Art. 13, 106, 147, 168, 211)
159 
160For IVRO, the self-employed person pays BOTH employer and employee portions:
161 
162| Branch | Total Rate (% of base salary) |
163|---|---|
164| Enfermedades y Maternidad (in kind, fixed) | approx. 20.40% |
165| Enfermedades y Maternidad (in kind, excess) | Varies by salary above 3 UMA |
166| Enfermedades y Maternidad (cash) | approx. 1.00% |
167| Invalidez y Vida | approx. 2.375% |
168| Retiro | 2.00% |
169| Cesantia en Edad Avanzada y Vejez | approx. 4.375% (increasing under 2020 reform) |
170| Guarderias | 1.00% |
171| Riesgos de Trabajo | approx. 0.54% (office/low-risk average) |
172| **Approximate total** | **approx. 31-33%** |
173 
174### 5.2 Modalidad 40 Contribution Rates (Art. 218)
175 
176| Component | Rate |
177|---|---|
178| Invalidez y Vida | approx. 2.375% |
179| Retiro | 2.00% |
180| Cesantia y Vejez | approx. 4.375% |
181| **Total** | **approx. 10.075%** |
182 
183Maximum base: 25 UMA daily.
184 
185### 5.3 Seguro de Salud para la Familia (Art. 240-245)
186 
187Annual cost per family member:
188 
189| Age Group | Annual Cost (approx. % of annual UMA) |
190|---|---|
191| Under 19 | approx. 5.9% |
192| 19-39 | approx. 7.5% |
193| 40-59 | approx. 9.1% |
194| 60+ | approx. 11.9% |
195 
196Payment: annual, upfront.
197 
198### 5.4 Tax Deductibility (ISR Art. 151)
199 
200| Contribution Type | Deductible? |
201|---|---|
202| IVRO contributions | Yes -- social security contribution deduction |
203| Modalidad 40 | Yes -- deductible for ISR |
204| Seguro de Salud para la Familia | Yes -- medical expense deduction (limited) |
205 
206### 5.5 Eligibility Rules
207 
208| Rule | Detail |
209|---|---|
210| IVRO eligibility | Self-employed workers, freelancers, independent professionals |
211| Modalidad 40 eligibility | Minimum 52 weeks prior contributions; must enrol within 5 years of last employer contribution |
212| Seguro de Salud eligibility | Any person not otherwise covered by IMSS |
213 
214### 5.6 2020 Reform Impact
215 
216The 2020 pension reform gradually increases the employer share of Cesantia en Edad Avanzada y Vejez from 3.15% (2023) to 11.875% (2030). For IVRO, the self-employed pays both shares, so total contribution increases annually through 2030.
217 
218---
219 
220## Section 6 -- Tier 2 Catalogue (Reviewer Judgement Required)
221 
222### 6.1 Choosing Between IVRO and Seguro de Salud
223 
224Freelancer wants health coverage only, no pension. Seguro de Salud is lower cost but accumulates no pension credits. If long-term retirement planning matters, IVRO is required. Flag for reviewer to assess retirement impact.
225 
226### 6.2 Choosing Salary Base for IVRO
227 
228Higher base = higher cost but higher pension and maternity/disability benefits. Common strategy: choose a base reflecting actual income for adequate coverage. Flag for reviewer to balance cost vs coverage.
229 
230### 6.3 Modalidad 40 as Pension Strategy
231 
232Modalidad 40 allows choosing up to 25 UMA base to maximize future pension. This is a common strategy for persons approaching retirement age. Flag for reviewer -- qualified advisor must assess pension projection.
233 
234### 6.4 Gap in Contributions
235 
236If client had employer IMSS, left more than 5 years ago with no contributions since, the Modalidad 40 right has lapsed. IVRO is the only voluntary option.
237 
238---
239 
240## Section 7 -- Working Paper Template
241 
242```
243MEXICO IMSS SELF-EMPLOYED WORKING PAPER
244Client: _______________ CURP: ___________ RFC: ___________
245Date: ___________
246 
247A. CURRENT STATUS
248 A1. Employment status ___________
249 A2. Currently enrolled in IMSS? ___________
250 A3. Prior IMSS weeks (semanas cotizadas) ___________
251 A4. Date of last employer contribution ___________
252 
253B. CHOSEN OPTION
254 B1. IVRO / Modalidad 40 / Seguro de Salud ___________
255 
256C. CONTRIBUTION CALCULATION
257 C1. Chosen base salary (daily UMA multiples) ___________
258 C2. Monthly base ___________
259 C3. Applicable rate ___________
260 C4. Monthly contribution ___________
261 C5. Annual contribution ___________
262 
263D. COVERAGE
264 D1. Health (Enfermedades y Maternidad) ___________
265 D2. Disability (Invalidez y Vida) ___________
266 D3. Pension (Retiro, Cesantia y Vejez) ___________
267 D4. Work Risk (Riesgos de Trabajo) ___________
268 D5. Childcare (Guarderias) ___________
269 
270E. TAX DEDUCTIBILITY
271 E1. ISR deduction type ___________
272 E2. Estimated ISR benefit ___________
273 
274REVIEWER FLAGS:
275 [ ] Employment status confirmed (self-employed only)?
276 [ ] Prior weeks verified for Modalidad 40 eligibility?
277 [ ] 5-year window checked for Modalidad 40?
278 [ ] UMA values verified with INEGI?
279 [ ] 2020 reform rate adjustments applied?
280```
281 
282---
283 
284## Section 8 -- Bank Statement Reading Guide
285 
286### Mexican Bank Statement Formats
287 
288| Bank | Format | Key Fields |
289|---|---|---|
290| BBVA Mexico (Bancomer) | CSV / PDF | Fecha, Descripcion, Cargo, Abono, Saldo |
291| Banorte | CSV | Fecha, Concepto, Retiro, Deposito, Saldo |
292| Citibanamex | CSV / PDF | Fecha, Descripcion, Cargos, Abonos, Saldo |
293| Santander Mexico | CSV | Fecha, Concepto, Cargo, Abono, Saldo |
294| HSBC Mexico | CSV | Fecha, Descripcion, Debito, Credito, Saldo |
295| Scotiabank Mexico | CSV | Fecha, Descripcion, Retiro, Deposito, Saldo |
296 
297### Key IMSS-Related Narrations
298 
299| Narration | Meaning | Classification Hint |
300|---|---|---|
301| IMSS CUOTA / PAGO IMSS | IMSS contribution | Social security -- personal deduction |
302| IMSS MOD 40 / MODALIDAD 40 | Modalidad 40 payment | Pension contribution -- personal deduction |
303| IMSS SSF / SEGURO SALUD | Family health insurance | Medical expense deduction |
304| INFONAVIT / PAGO INFONAVIT | Housing fund payment | Separate from IMSS |
305| PENSION IMSS / RETIRO IMSS | Pension receipt | Taxable pension income |
306 
307---
308 
309## Section 9 -- Onboarding Fallback
310 
311If the client provides a bank statement but cannot answer onboarding questions immediately:
312 
3131. Identify all IMSS-related debits (contributions paid)
3142. Classify as personal deductions (NOT business expenses)
3153. Flag Modalidad 40 payments separately from IVRO
3164. Do NOT assume eligibility for any programme without confirmation
317 
318Present these questions:
319 
320```
321ONBOARDING QUESTIONS -- MEXICO IMSS SELF-EMPLOYED
3221. Are you purely self-employed, or also employed part-time?
3232. Are you currently enrolled in any IMSS regime? If so, which one?
3243. What is your CURP and RFC?
3254. How many weeks have you contributed to IMSS in total (semanas cotizadas)?
3265. If you were previously employed, when was your last employer IMSS contribution?
3276. Which family members do you want to cover (spouse, children, parents)?
3287. What salary base do you want for your contributions?
3298. Are you interested in health coverage, pension coverage, or both?
330```
331 
332---
333 
334## Section 10 -- Reference Material
335 
336### Key Legislation
337 
338| Topic | Reference |
339|---|---|
340| IMSS coverage branches | LSS Art. 6, 11 |
341| IVRO voluntary enrolment | LSS Art. 13 |
342| Modalidad 40 | LSS Art. 218 |
343| Seguro de Salud para la Familia | LSS Art. 240-245 |
344| Contribution rates | LSS Art. 106, 147, 168, 211 |
345| ISR deductibility | Ley del ISR Art. 151 |
346| UMA usage | Decreto DOF 27/01/2016 |
347| 2020 pension reform | Reforma LSS 2020 (Cesantia rates) |
348 
349### Known Gaps / Out of Scope
350 
351- Employer-employee IMSS obligations
352- IMSS disability claims processing
353- INFONAVIT credit interaction
354- ISSSTE (public sector social security)
355- Pension calculation projections (require actuarial analysis)
356 
357### Changelog
358 
359| Version | Date | Change |
360|---|---|---|
361| 2.0 | April 2026 | Full rewrite to v2.0 structure; bank statement patterns; worked examples |
362| 1.0 | 2025 | Initial version |
363 
364### Self-Check
365 
366- [ ] Employment status confirmed as self-employed?
367- [ ] Prior IMSS weeks verified before Modalidad 40 recommendation?
368- [ ] 5-year Modalidad 40 window checked?
369- [ ] UMA values verified with INEGI for current year?
370- [ ] 2020 reform rate increases applied?
371- [ ] Contributions classified as personal deductions (NOT business expenses)?
372 
373---
374 
375## PROHIBITIONS
376 
377- NEVER enrol in Modalidad 40 without verifying at least 52 weeks of prior contributions
378- NEVER assume Seguro de Salud para la Familia provides pension or disability coverage -- it is health only
379- NEVER use salario minimo for IMSS calculations -- use UMA since 2017
380- NEVER ignore the 5-year window for Modalidad 40 enrolment after leaving employment
381- NEVER assume IVRO rates are fixed -- the 2020 reform increases Cesantia rates annually through 2030
382- NEVER present IMSS calculations as exact -- use the IMSS calculator at imss.gob.mx for precise amounts
383- NEVER advise on Modalidad 40 as a pension strategy without flagging for a qualified advisor
384- NEVER classify IMSS contributions as business expenses -- they are personal deductions under ISR Art. 151
385- NEVER present calculations as definitive -- always label as estimated and direct client to IMSS or a qualified Mexican contador publico
386 
387---
388 
389## Disclaimer
390 
391This skill and its outputs are provided for informational and computational purposes only and do not constitute tax, legal, or financial advice. Open Accountants and its contributors accept no liability for any errors, omissions, or outcomes arising from the use of this skill. All outputs must be reviewed and signed off by a qualified professional (such as a contador publico, social security specialist, or equivalent licensed practitioner in Mexico) before filing or acting upon.
392 
393The most up-to-date, verified version of this skill is maintained at [openaccountants.com](https://openaccountants.com). Log in to access the latest version, request a professional review from a licensed accountant, and track updates as tax law changes.
394 

Run this skill, then get an accountant to check it

After running the full skill pack in your AI agent, sign up and upload your worksheet. We'll connect you with a trusted accountant in our network who can review your numbers before you file.

Quality

Q3: AI-drafted

AI-generated with structure and citations. Not independently verified.

Needs deep research against tax authority websites to reach Q2.

Accountant Review

Not yet reviewed
0/36

About

Use this skill whenever asked about Mexican IMSS social security for self-employed individuals. Trigger on phrases like "IMSS", "seguro social Mexico", "regimen voluntario", "incorporacion voluntaria", "IMSS freelancer", "aseguramiento voluntario", "Modalidad 40", or any question about voluntary IMSS enrollment, contribution calculation, or benefits for self-employed persons in Mexico. Covers voluntary inscription (Modalidad 40, regimen voluntario), contribution bases, health/maternity/retirement/disability benefits, and tax deductibility. ALWAYS read this skill before touching any Mexican IMSS work.

MXty-2025

Use this skill

This skill is open source and free to use in any AI agent. Copy it, download it, or clone the repo. If you find an error, flag it — a licensed accountant will review.

4 of 6 in the MX workflow: