A new report from Metro2, the validation platform built by Switch Labs, points to a familiar culprit behind rejected furnisher files: the data fields that identify a consumer and an account, not the loan itself.
Released last week, the analysis found that a missing or non-unique account number was the single most common reason files failed validation, appearing in 52.1% of failed files and across the widest range of furnishers in the sample. Because the account number is how a credit bureau matches this month’s tradeline to prior months, a blank or shifting identifier fragments an account’s history or spawns duplicates, even though it looks like a minor data field.
The findings carry direct relevance for the collection agencies, debt buyers, and lenders that furnish data to the nationwide credit reporting agencies. Metro2 drew its numbers from 432 production files run through its validation pipeline between June 2025 and June 2026, representing 25 distinct furnishers. Of those, 71 files across 12 furnishers failed, generating more than 8,500 individual findings against the Credit Reporting Resource Guide rule set published by the Consumer Data Industry Association.
Beyond account numbers, the most frequent failures clustered around address and identity fields. Invalid or missing state codes appeared in 16.9% of failed files, followed by invalid ECOA codes and malformed ZIP codes, each at 15.5%. Missing first names and invalid account status codes each turned up in 14.1% of failed files, while placeholder ZIP values such as 00000, a telltale sign that test data was never purged before go-live, surfaced in 12.7%.
The company groups the root causes into three buckets, all preventable upstream: field-mapping gaps where the source system holds the data but never routes it to the correct Metro 2 field, incomplete onboarding records that surface as missing address components months later, and leftover test data. Its prescription is to validate every file against the full CRRG rule set before submission rather than after a bureau rejection, and to fix the mapping once instead of chasing rejections each cycle.
Metro2 was candid about the limits of the data, describing it as an early read on a small, recent sample rather than a population study, with rankings that are directional and will be refreshed as volume grows. The report also draws a line between furnishing and dispute resolution, noting that errors caught before submission never reach a consumer’s report, while disputes about already-furnished data run through the bureaus’ separate e-OSCAR platform.
