We removed 12 suppliers from the Mango platform in Q4 2024. Of those 12, 9 were removed for delivery performance failures — on-time delivery rates below our 85% threshold over a 90-day window. Two were removed for tax compliance issues that surfaced in a quarterly audit. One was removed because they could not provide certifications for a grade of rebar they had been selling as certified stock.
Removing suppliers is not something we do lightly. Each removal disrupts contractor relationships and requires us to source replacement coverage for affected SKU categories. But the alternative — keeping underperforming suppliers because switching costs are high — transfers the cost to contractors in missed deadlines, project delays, and materials that fail inspection.
Here is the full checklist we run before approving a supplier and the metrics we track quarterly to decide whether they stay.
Check 1: RFC Compliance and Tax Status
Every supplier on the Mango platform must have a valid RFC (Registro Federal de Contribuyentes) and be in active status with SAT (the Mexican tax authority). This check takes about 20 minutes using SAT's public verification portal. We verify RFC at onboarding and re-verify quarterly as part of our supplier audit cycle.
Why this matters for contractors: when you receive a CFDI (invoice) from a supplier, the invoice is only valid for tax deduction purposes if the supplier is in active RFC status at the time of issue. If a supplier issues you an invoice while their RFC is suspended — which can happen due to unfiled returns or a tax dispute — the invoice may be invalidated retroactively by SAT. The contractor ends up unable to deduct the expense and potentially faces a tax audit. This happened to three contractors in our beta cohort who had purchased from a supplier that had an RFC suspension for 8 months without knowing it.
Suppliers with any open tax disputes or SAT enforcement actions are ineligible regardless of their delivery performance. This is a hard disqualifier.
Check 2: Physical Inventory Verification
We visit every supplier's primary warehouse before listing them on the platform. The visit has two purposes: confirming they have the physical inventory capacity to fulfill the order volumes we expect, and verifying that the materials they plan to list meet the specifications they claim.
For cement suppliers, we pull samples from at least 3 different production batches and verify compressive strength ratings against the listed NOM (Norma Oficial Mexicana) certification. For rebar, we check that the grade markings on the physical bars match the grade listed in the supplier's catalogue. In the Q4 2024 removal, the supplier who was listing Grade 60 rebar had physical inventory that was a mix of Grade 60 and Grade 42 from different production runs stored in the same bin. They could not verify which was which without re-testing the entire lot.
Suppliers who cannot produce certification documentation for materials claiming NOM certification are rejected at this stage.
Check 3: Delivery Infrastructure Review
A supplier who has the right materials at the right price but cannot reliably deliver them is not useful to a contractor on a schedule. Before onboarding, we assess the supplier's delivery fleet: number of vehicles, payload capacity, GPS tracking capability, and service area.
Our minimum standard for suppliers covering the CDMX metropolitan area: at least 3 delivery vehicles with a combined payload capacity of 15 tons or more, operational GPS tracking on all vehicles, and delivery availability Monday through Saturday. Suppliers with fewer than 3 vehicles get restricted to specific material categories where their volume is manageable with a smaller fleet.
We also assess warehouse proximity to the primary delivery zones. Suppliers whose warehouse is in Ecatepec serving delivery routes in Coyoacán have a structural disadvantage in meeting 48-hour delivery windows due to transit time through the CDMX traffic grid. We account for this in our routing algorithm and do not commit 48-hour delivery from suppliers whose warehouse location makes it geometrically unlikely for specific zones.
Check 4: Quality Certification Documentation
Beyond the physical inspection, we require current certification documentation. The specific certifications required depend on the material category. For structural materials — cement, rebar, concrete blocks — we require current NOM certification. For electrical materials, we require NOM-001-SEDE certification compliance. For plumbing, NOM-008-ENER and NOM-009-ENER as applicable.
Certification documents must be dated within the past 24 months. Certifications older than 24 months require a re-certification audit before the supplier is listed. We track certification renewal dates and flag suppliers 60 days before their certifications expire. Suppliers who let certifications lapse during active listing are immediately suspended from new order acceptance until the certification is renewed.
Check 5: Reference Check From Three Active Buyers
Before finalizing onboarding, we request contact information for three contractors who have purchased from the supplier in the past 12 months. We contact all three with a structured 8-question survey covering: delivery accuracy, materials quality, communications responsiveness, invoice accuracy, returns handling, and overall satisfaction.
We look for consistent patterns, not individual opinions. A supplier with two positive references and one outlier negative is normal. A supplier with two positive references and one who describes systematic short deliveries is a signal that the short delivery problem is selective, which is more concerning than random quality variation.
Reference check results that fall below 7/10 average on delivery accuracy are a disqualifier regardless of the supplier's other qualifications.
Check 6: Pricing and Catalogue Accuracy Review
We benchmark every supplier's initial catalogue pricing against the current market rate for that material category. We use a combination of published price indices from INEGI (the National Institute of Statistics and Geography), spot checks from competing suppliers, and our internal pricing data from existing catalogue entries.
Suppliers whose initial catalogue pricing is more than 12% above market in any category are asked to revise before listing. The 12% threshold accounts for legitimate regional variation in delivery cost. Pricing above 12% market premium is not a quality signal — it usually reflects a supplier who prices for their existing relationship network and has not calibrated for a competitive marketplace.
More importantly, we audit catalogue accuracy: do the listed dimensions, grades, and certifications match the physical inventory? Any material listed with specifications that cannot be verified against documentation is removed from the catalogue pending verification. Suppliers with more than 5% of their catalogue SKUs flagged for unverifiable specifications are not activated until the catalogue is cleaned.
Check 7: Financial Stability Review
We request two years of financial statements or tax returns from prospective suppliers. This is the check that creates the most friction in the onboarding process — many small and mid-size suppliers are reluctant to share financial information with a platform they are just starting to work with.
We explain the reason: when a supplier becomes financially stressed, delivery performance deteriorates before they notify us. They start prioritizing their longest-standing customers, delaying platform deliveries to preserve those relationships. By the time contractors notice a drop in delivery performance, the supplier may be 60 days from closing. Financial review is not about policing suppliers — it is about predicting which suppliers are at risk of disrupting contractor project timelines.
We look specifically at: revenue trend over the past two years (declining revenue is a yellow flag), accounts receivable aging (a supplier with 40% of receivables over 90 days is under cash pressure), and debt-to-asset ratio. Suppliers who decline to share financial information are listed provisionally with a lower order volume cap until they complete the financial review.
Quarterly Review: How We Decide Who Stays
Onboarding verification is the entrance exam. The quarterly review is the ongoing grade. We track four metrics for every active supplier on a rolling 90-day basis: on-time delivery rate (target 90%+), short delivery rate (deliveries where quantity received is less than quantity ordered, target below 2%), return rate (materials returned for quality or specification failure, target below 1%), and invoice accuracy rate (invoices issued matching the actual order, target 98%+).
A supplier who drops below threshold on one metric in a single quarter receives a formal notice and a 30-day improvement window. A supplier below threshold on two or more metrics simultaneously, or who misses the improvement window after a notice, is suspended from new order acceptance. We notify the affected contractors 48 hours before suspension takes effect and route their pending orders to backup suppliers in the same category.
The 12 removals in Q4 2024 were all cases where the 30-day improvement window did not produce measurable change. In 7 of those 9 delivery-related removals, the root cause was the same: insufficient vehicle fleet to handle the volume growth on the platform combined with under-investment in scheduling software. The suppliers were not malicious — they were operating a 2019-era delivery operation at a 2024 volume level and hoping the gap would not show up in metrics.
It did. Contractors felt it first.
If you are a supplier who wants to list on the Mango platform and you meet these criteria, contact us at contact@mangxo.org with "Supplier Application" in the subject line. Include your RFC, the material categories you cover, and your delivery service area. We will respond within 3 business days with the full onboarding questionnaire.