mx-return-assembly

Mexico Return Assembly -- Orchestrator Skill v1.0

Section 1 -- Quick Reference

Quick Reference

Field	Value
Country	Mexico (Estados Unidos Mexicanos)
Tax	ISR (Impuesto Sobre la Renta) -- Declaración Anual
Currency	MXN (Peso Mexicano) only
Tax year	Calendar year (1 January -- 31 December)
Primary legislation	Ley del Impuesto Sobre la Renta (LISR), Código Fiscal de la Federación (CFF)
Tax authority	Servicio de Administración Tributaria (SAT)
Filing portal	sat.gob.mx -- Declaraciones
Filing deadline	April 30 of following year (personas físicas)
Required credential	e.firma (FIEL) or Contraseña SAT
Validated by	Pending — requires sign-off by a Mexican Contador Público
Skill version	1.0

ISR Annual Table -- Actividad Empresarial y Profesional (Art. 152 LISR, 2025)

ISR Annual Table -- Actividad Empresarial y Profesional (Art. 152 LISR, 2025) (Art. 152 LISR, 2025)

Lower Limit (MXN)	Upper Limit (MXN)	Fixed Quota (MXN)	Rate on Excess
0.01	8,952.49	0.00	1.92%
8,952.50	75,984.55	171.88	6.40%
75,984.56	133,536.07	4,461.94	10.88%
133,536.08	155,229.80	10,723.55	16.00%
155,229.81	185,852.57	14,194.54	17.92%
185,852.58	374,837.88	19,682.13	21.36%
374,837.89	590,795.99	60,049.40	23.52%
590,796.00	1,127,926.84	110,842.74	30.00%
1,127,926.85	1,503,902.46	271,981.99	32.00%
1,503,902.47	4,511,707.37	392,294.17	34.00%
4,511,707.38	En adelante	1,414,947.85	35.00%

RESICO Annual ISR Table (Art. 113-E LISR)

RESICO Annual ISR Table (Art. 113-E LISR) (Art. 113-E LISR)

Annual Income (MXN)	Rate
Up to $300,000	1.00%
Up to $600,000	1.10%
Up to $1,000,000	1.50%
Up to $2,500,000	2.00%
Up to $3,500,000	2.50%

Section 2 -- Assembly Workflow

Phase 1: Data Gathering

1. Download CFDI emitidos (issued) from SAT portal -- full year XML set
2. Download CFDI recibidos (received) from SAT portal -- full year XML set
3. Obtain bank statements (all accounts, all institutions)
4. Obtain acuses de declaraciones provisionales (ISR + IVA, all months)
5. Obtain constancias de retenciones (employers, clients with retention, platforms)
6. Obtain IMSS payment receipts (if voluntary or employer)
7. Obtain prior year declaración anual (for comparison)

Phase 2: CFDI Revenue Reconciliation

Phase 2: CFDI Revenue Reconciliation

Step	Check	Action if Mismatch
2.1	Sum all CFDI emitidos (subtotal, before IVA)	This = gross revenue for ISR
2.2	Compare CFDI total vs bank deposits	Bank > CFDI = possible undeclared income
2.3	Verify método de pago (PUE vs PPD)	PPD: income = when complemento de pago issued
2.4	Check for cancelled CFDI (status = cancelado)	Exclude cancelled from totals
2.5	Verify RFC of all clients on CFDI	Flag any RFC genérico (XAXX010101000) > $50,000
2.6	Cross-reference CFDI vs client payments	Identify unpaid invoices (for PPD accounting)

• RESICO Special Rule — Income is recognised on cash basis (efectivamente cobrado). Only CFDI with confirmed payment count. PPD CFDI without complemento de pago = not yet income.
• AEP Rule — Income recognised on accrual basis (devengado) for general regime, OR cash basis if elected under Art. 196 CFF. Verify which method the client uses. (Art. 196 CFF)

Phase 3: CFDI Expense Reconciliation (AEP Only)

Phase 3: CFDI Expense Reconciliation (AEP Only)

Step	Check	Action if Mismatch
3.1	Sum all CFDI recibidos (deductible expenses)	Verify each has valid RFC, correct régimen fiscal
3.2	Verify requisitos de deducibilidad (Art. 27 LISR)	Payment via banked method >$2,000 MXN
3.3	Check IVA on each CFDI recibido	IVA trasladado = IVA acreditable
3.4	Verify payment method	Cash payments >$2,000 = NOT deductible
3.5	Check timing	Expense must be in same fiscal year
3.6	Verify proportionality	If mixed use, apply proportion

• Deductibility Requirements (Art. 27 LISR) — Strictly indispensable for the business activity; Backed by valid CFDI; Paid by transfer, cheque, credit/debit card, or electronic wallet (>$2,000); Withholding obligations met (if applicable); Properly registered in accounting (Art. 27 LISR)

Phase 4: Provisional ISR vs Annual ISR Cross-Check

Phase 4: Provisional ISR vs Annual ISR Cross-Check

Step	Check	Expected Outcome
4.1	Sum all provisional ISR payments made	Total from acuses
4.2	Sum all ISR retained by clients (retenciones)	From constancias de retenciones
4.3	Calculate annual ISR liability	Using Art. 152 table (AEP) or Art. 113-E (RESICO)
4.4	Annual ISR - provisionals - retentions	= ISR a cargo (to pay) or ISR a favor (refund)
4.5	If saldo a favor > 30% of ISR annual	Flag -- high refund ratio triggers SAT review

• RESICO Cross-Check — Annual ISR = total income × applicable RESICO rate; Credit: sum of monthly provisional payments; Credit: retenciones (1.25% retained by personas morales); Result = a cargo or a favor
• AEP Cross-Check — Annual ISR = progressive table on (revenue - deductions - personal deductions); Credit: provisional payments (Art. 106 method); Credit: retenciones; Credit: estímulos fiscales (if applicable) (Art. 106 method)

Phase 5: IVA Monthly Reconciliation

Phase 5: IVA Monthly Reconciliation

Step	Check	Expected Outcome
5.1	IVA trasladado (charged to clients)	16% × revenue (or 8% border, 0% applicable)
5.2	IVA acreditable (paid on expenses)	Sum IVA on deductible CFDI recibidos
5.3	IVA retenido (retained by clients)	From constancias de retenciones (2/3 IVA common)
5.4	Monthly: trasladado - acreditable - retenido	= IVA a cargo or a favor
5.5	Cross-check vs monthly declaraciones filed	Verify consistency
5.6	Annual IVA total	Should = sum of 12 monthly declarations

• Common IVA Retentions — Persona moral paying persona física: retains 2/3 of IVA (Art. 1-A LIVA); Digital platform: retains 100% IVA; Government entities: retain 100% IVA (Art. 1-A LIVA)

Phase 6: IMSS Cuotas Check

Phase 6: IMSS Cuotas Check (Art. 151-V)

Item	Check
Voluntary (Modalidad 40)	Verify 12 monthly payments made
Employer (patrón)	Verify SUA/IDSE bimestral payments (6 periods)
Cuotas amount	Verify base declared × contribution rate
Deductibility	AEP: deductible as personal deduction (Art. 151-V). RESICO: NOT deductible.

Phase 7: Personal Deductions (AEP Annual Return)

Phase 7: Personal Deductions (AEP Annual Return) (Art. 151 LISR)

Deduction (Art. 151 LISR)	Limit	Notes
Medical/dental/hospital expenses	No global limit per item	Must be for taxpayer, spouse, ascendants, descendants
Funeral expenses	1 UMA anual ($41,273.52)	Per event
Donations	Up to 7% of prior year base (4% to gobierno)	Must be to donatarias autorizadas
Mortgage interest (real, vivienda)	Up to 750,000 UDIS of credit	Only habitual residence
Voluntary retirement savings (Afore/PPR)	10% of income, max 5 UMA anuales ($206,367.60)	Deductible contribution to Plan Personal de Retiro
Health insurance premiums	No specific sub-limit	Complementary medical insurance
School transportation	Per child	Only if mandatory
Local taxes on property	Actual paid	Predial on property owned

• Global Personal Deduction Limit — The lesser of 15% of total income OR 5 UMA anuales (MXN$206,367.60 for 2025).

Section 3 -- Computation Engine

RESICO Annual Computation

• RESICO Annual Computation — A. Total CFDI emitidos efectivamente cobrados (excl. IVA) ___________ B. Apply RESICO annual table rate ___________ C. ISR del ejercicio (A × rate from table) ___________ D. Less: Pagos provisionales ISR ___________ E. Less: Retenciones ISR (1.25% from personas morales) ___________ F. ISR a cargo / (a favor) = C - D - E ___________

AEP Annual Computation

• AEP Annual Computation — A. INGRESOS ACUMULABLES A1. CFDI emitidos (net of IVA) ___________ A2. Other income (interest, etc.) ___________ A3. Total income ___________ B. DEDUCCIONES AUTORIZADAS B1. Purchases and cost of sales ___________ B2. Operating expenses (backed by CFDI) ___________ B3. Depreciation (inversiones -- Art. 31--38 LISR) ___________ B4. Insurance premiums ___________ B5. Sueldos y salarios (employees) ___________ B6. Cuotas IMSS patronales ___________ B7. Total deducciones autorizadas ___________ C. UTILIDAD FISCAL (A3 - B7) ___________ D. PÉRDIDAS FISCALES DE EJERCICIOS ANTERIORES ___________ E. BASE GRAVABLE (C - D) ___________ F. DEDUCCIONES PERSONALES (Art. 151) ___________ G. BASE PARA TARIFA (E - F) ___________ H. ISR (apply Art. 152 table to G) ___________ I. Less: Subsidio para el empleo (if applicable) ___________ J. Less: Pagos provisionales ___________ K. Less: Retenciones ___________ L. ISR A CARGO / (A FAVOR) = H - I - J - K ___________ (Art. 31-38 LISR; Art. 151; Art. 152)

Section 4 -- Cross-Check Matrix

Cross-Check Matrix

Cross-Check	Source A	Source B	Tolerance	Flag If
Revenue integrity	CFDI emitidos total	Bank deposits total	±5%	Bank > CFDI by >5%
Expense backing	CFDI recibidos total	Declared deductions	Exact	Deduction without CFDI
IVA consistency	Monthly IVA filed	CFDI-derived IVA	Exact	Mismatch any month
Provisional ISR	Sum of acuses	SAT portal query	Exact	Missing month
Retentions	Constancias received	Annual pre-filled data	Exact	Amount differs
IMSS cuotas	SUA receipts	Declared personal deduction	Exact	Over-claimed
DIOT consistency	Monthly DIOT filed through SAT online platform	CFDI recibidos	±1%	Material difference

Section 5 -- Filing Procedure

Pre-Filing Checklist

[ ] All 12 provisional ISR declarations filed (or complementarias submitted) [ ] All 12 IVA monthly declarations filed [ ] All 12 DIOT submissions filed through SAT online DIOT platform (mandatory since Aug. 1, 2025) [ ] All constancias de retenciones obtained [ ] CFDI emitidos reconciled to bank [ ] CFDI recibidos reconciled to expenses [ ] Personal deductions verified with documentation [ ] Prior year pérdidas fiscales confirmed (if carrying forward) [ ] Opinión de cumplimiento 32D positive (recommended)

Filing Steps (SAT Portal)

1. Log into sat.gob.mx with e.firma or Contraseña
2. Navigate to Declaraciones > Anuales > Personas Físicas
3. Select ejercicio fiscal
4. SAT pre-fills income from CFDI and retentions -- VERIFY
5. Enter deductions, personal deductions, other income
6. System calculates ISR a cargo / a favor
7. If a cargo: generate línea de captura (payment reference)
8. If a favor: elect devolución (refund via CLABE) or compensación
9. Sign with e.firma and submit
10. Download acuse de recibo (proof of filing)

Payment Options (ISR a Cargo)

Payment Options (ISR a Cargo)

Method	Deadline	Notes
Single payment	April 30	Full amount, no surcharge
Pago en parcialidades	Within 30 days of filing	Up to 6 instalments; generates recargos
Línea de captura	Valid 5 business days	Generated at filing; must pay before expiry

Refund Process (ISR a Favor)

Refund Process (ISR a Favor)

Amount	Process	Timeline
≤MXN$150,000	Automatic via Contraseña	5--40 business days
>MXN$150,000	Requires e.firma signature	40 business days max (legal)
>MXN$500,000	SAT may request additional documentation	Up to 90 days with audit
Refund not received	Verify CLABE matches RFC holder	Check estatus at sat.gob.mx

Section 6 -- Edge Cases

Dual Régimen in Same Year (RESICO → AEP Transition)

• Dual Régimen in Same Year (RESICO → AEP Transition) — If income exceeds $3.5M mid-year, recalculate entire year under AEP; Credit all RESICO provisional payments against AEP annual liability; File declaración complementaria for all provisional months; Update Constancia de Situación Fiscal

Multiple Income Chapters (Acumulación)

• Multiple Income Chapters (Acumulación) — When taxpayer has income from multiple chapters: Sueldos y salarios (Cap. I) + AEP (Cap. II): accumulate both in annual; RESICO + Sueldos: RESICO is separate (no accumulation unless >$300,000 combined); Arrendamiento + AEP: both accumulate in annual declaration; Apply progressive table to total accumulated base

Pérdidas Fiscales (Tax Losses)

• Pérdidas Fiscales (Tax Losses) — AEP losses carry forward up to 10 years (Art. 109 LISR); Update for inflation annually (factor de actualización); Cannot offset losses against RESICO income; RESICO does NOT generate tax losses (no deductions allowed) (Art. 109 LISR)

Estímulos Fiscales (Tax Incentives)

Estímulos Fiscales (Tax Incentives)

Incentive	Article	Benefit
Technological research/development	Art. 202 LISR	30% credit on R&D spending
Film/theatre production	Art. 189-190 LISR	Credit against ISR
Northern border region	Decree 2019	ISR rate reduced to 20%; IVA 8%
Donations to trusts	Art. 151 LISR	7% limit

Section 7 -- Red Flags and Audit Triggers

Red Flags and Audit Triggers

Indicator	SAT Risk Level	Action
Bank deposits > CFDI revenue by >20%	HIGH	Investigate -- potential discrepancia fiscal
ISR refund > 40% of annual liability	MEDIUM	Document thoroughly; expect SAT query
Zero CFDI for months with bank activity	HIGH	File complementarias or explain
CFDI to RFC genérico > $50,000 individual	MEDIUM	SAT flags for review
Provisional payments all in ceros despite income	HIGH	Immediate regularisation needed
Deductions > 60% of revenue	MEDIUM	Verify each deduction meets Art. 27
Personal deductions near global limit	LOW	Normal -- just document properly
Year-over-year revenue drop > 50%	MEDIUM	SAT may compare to CFDI history

Section 8 -- Penalties Reference

Penalties Reference

Infraction	Penalty	Legal Basis
Late annual filing	MXN$1,810 -- $22,400 per requerimiento	CFF Art. 82
Omitted income (discovered by SAT)	55% -- 75% of omitted tax	CFF Art. 76
Failure to issue CFDI	MXN$19,700 -- $112,650 per CFDI	CFF Art. 84
Late payment (recargos)	CCP rate × 1.5 (approximately 1.47%/month in 2025)	CFF Art. 21
False CFDI (operations simuladas)	55% -- 75% + criminal liability	CFF Art. 69-B, 113 Bis
Failure to file DIOT	MXN$10,490 -- $20,970	CFF Art. 81-82

Section 9 -- Reference Material

Reference Material

Topic	Reference
ISR personas físicas	LISR Título IV
RESICO	LISR Art. 113-E to 113-J
AEP	LISR Título IV, Cap. II, Sección I
Annual progressive table	LISR Art. 152
Deductibility requirements	LISR Art. 27, 28
Personal deductions	LISR Art. 151
Tax losses	LISR Art. 109, 110
IVA	LIVA Art. 1--43
CFDI	CFF Art. 29, 29-A; RMF 2.7.x
Penalties	CFF Art. 76--82
Recargos	CFF Art. 21
DIOT	LIVA Art. 32
SAT portal	sat.gob.mx
RMF 2025	Resolución Miscelánea Fiscal 2025 (DOF)

Disclaimer

This 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 Público Certificado, or equivalent licensed practitioner in your jurisdiction) before filing or acting upon.

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Section 2 -- Assembly Workflow

0. Data Gathering — Download CFDI emitidos/recibidos, bank statements, acuses, constancias, IMSS receipts, prior year return

Phase 2: CFDI Revenue Reconciliation

0. CFDI Revenue Reconciliation — Reconcile CFDI emitidos against bank deposits and payment methods

Phase 3: CFDI Expense Reconciliation (AEP Only)

0. CFDI Expense Reconciliation — Reconcile CFDI recibidos against deductibility requirements

Phase 4: Provisional ISR vs Annual ISR Cross-Check

0. Provisional vs Annual ISR Cross-Check — Cross-check provisional payments and retentions against annual ISR liability

Phase 5: IVA Monthly Reconciliation

0. IVA Monthly Reconciliation — Reconcile IVA trasladado, acreditable, and retenido monthly and annually

Phase 6: IMSS Cuotas Check

0. IMSS Cuotas Check — Verify IMSS cuotas payments and deductibility

Phase 7: Personal Deductions (AEP Annual Return)

0. Personal Deductions Verification — Verify personal deductions against Art. 151 limits

Section 3 -- Computation Engine

0. Computation Engine — Run RESICO or AEP annual computation as applicable

Section 4 -- Cross-Check Matrix

0. Cross-Check Matrix — Apply full cross-check matrix across all data sources

Section 5 -- Filing Procedure

0. Filing Procedure — Complete pre-filing checklist and file via SAT portal