How to Choose a PAC for Mexican E-Invoicing: Provider Selection Guide

Every CFDI issued in Mexico must be certified by a PAC (Proveedor Autorizado de Certificación) — a SAT-authorized company that validates, stamps, and registers your electronic invoices. As of 2026, SAT lists approximately 70 active PACs, ranging from free basic services to enterprise platforms costing MXN 5,000+/month.

What Is a PAC and Why Do You Need One?

a PAC and Why Do You Need One includes: Receive your signed CFDI XML Validate all fields against SAT rules (RFC, amounts, codes)

A PAC is a private company authorized by SAT to validate CFDI documents, apply the Timbre Fiscal Digital (SAT's digital stamp), and register invoices with SAT's central database. No CFDI is fiscally valid without PAC certification — this is not optional. The PAC's role in the CFDI process:

1. Receive your signed CFDI XML
2. Validate all fields against SAT rules (RFC, amounts, codes)
3. Apply the Timbre Fiscal Digital (UUID + SAT stamp)
4. Return the certified CFDI to your system
5. Report the CFDI to SAT's central repository

How to Evaluate PAC Providers

Key Selection Criteria

Criterion	What to Look For	Why It Matters
Uptime SLA	99.9%+ availability	PAC downtime means you can't issue valid invoices
Certification speed	<2 seconds per CFDI	Slow PACs create bottlenecks for high-volume issuers
API quality	REST/SOAP with good documentation	Critical for software integration
Complemento support	Pago 2.0, Nómina 1.2, Comercio Exterior 2.0	Needed if you issue payment receipts, payroll, or export CFDIs
Pricing model	Per-CFDI vs flat monthly	Per-CFDI is better for low volume; flat rate for high volume
Support	Phone/chat in business hours	SAT rule changes require quick PAC updates

PAC Pricing Models

• Free PACs: SAT offers free certification through some PACs for very low volume (typically <50 CFDIs/month). Limited features and slower response times.
• Per-CFDI pricing: MXN 1–5 per CFDI (approx. USD 0.05–0.28). Good for businesses issuing 50–500 CFDIs/month.
• Flat monthly plans: MXN 500–5,000/month for unlimited or high-volume certification. Best for 500+ CFDIs/month.
• Enterprise agreements: Custom pricing for 10,000+ CFDIs/month with SLAs and dedicated support.

How to Switch PACs

Choose your new PAC and complete their registration process Update your invoicing software's PAC API credentials

Switching PACs is straightforward because the CFDI format is standardized:

1. Choose your new PAC and complete their registration process
2. Update your invoicing software's PAC API credentials
3. Test with a few CFDIs to verify certification works
4. Switch production traffic to the new PAC
5. Historical CFDIs remain valid regardless of which PAC certified them

How Invoicemonk Integrates With PACs

Invoicemonk includes built-in PAC integration, handling the certification process transparently. You don't need to manage PAC relationships separately — our system selects the optimal certified provider and handles all API communication, retries, and status tracking.