MX Return Assembly

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)

| 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 accountingArt. 27 LISR

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

| 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% IVAArt. 1-A LIVA

Phase 6: IMSS Cuotas Check

| 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. |Art. 151-V

Phase 7: Personal Deductions (AEP Annual Return)

| 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 |Art. 151 LISR

Global Personal Deduction Limit

The lesser of 15% of total income OR 5 UMA anuales (MXN$206,367.60 for 2025).

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

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

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 |

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)

| 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 |

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)

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)

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)

| 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 |

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 |

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 |

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) |

Data Gathering

Download CFDI emitidos/recibidos, bank statements, acuses, constancias, IMSS receipts, prior year return

CFDI Revenue Reconciliation

Reconcile CFDI emitidos against bank deposits and payment methods

CFDI Expense Reconciliation

Reconcile CFDI recibidos against deductibility requirements

Provisional vs Annual ISR Cross-Check

Cross-check provisional payments and retentions against annual ISR liability

IVA Monthly Reconciliation

Reconcile IVA trasladado, acreditable, and retenido monthly and annually

IMSS Cuotas Check

Verify IMSS cuotas payments and deductibility

Personal Deductions Verification

Verify personal deductions against Art. 151 limits

Computation Engine

Run RESICO or AEP annual computation as applicable

Cross-Check Matrix

Apply full cross-check matrix across all data sources

Filing Procedure

Complete pre-filing checklist and file via SAT portal