Metro 2 ECOA Code 1: Individual (Sole Responsibility)

Specification

Code	1
Meaning	Individual (Sole Responsibility)
Field	ECOA Code (Field 10)
Record	Base Segment
Length / position	1 char · 63–63
Category	Sole Liability
CRRG reference	CRRG ECOA Code table (Base Segment)

Means sole contractual liability, not sole use. A borrower who lets a family member use the card is still ECOA 1 unless that person was actually added to the account as an authorized user with their own segment.
Does not mean "unmarried". Marital status is irrelevant to this code; what matters is whose signature is on the contract. A married borrower who applied alone and signed alone is ECOA 1.
Does not mean "no one else is on the account". If a second person signed, the correct code is 2, 5 or 7 depending on how they signed, and that person needs their own associated-consumer segment.
An account reported as ECOA 1 should carry no associated-consumer segments at all. A J1 or J2 segment attached to an ECOA 1 Base Segment is an internal contradiction unless that segment carries the authorized-user code.

1A credit union books a 60-month new-auto loan for a single applicant who qualified on their own income and is the sole signer on the retail installment contract.
2An online lender originates an unsecured personal loan to one borrower with no co-signer and no guarantor.
3A card issuer opens a revolving card for an individual applicant who never adds an authorized user.
4A property manager furnishes a residential lease held in one tenant's name only, with no co-tenant on the lease.

Use ECOA 1 whenever exactly one person is contractually obligated, regardless of who is actually making the payments.
Do not switch an account from 1 to 2 because a spouse started paying it. Liability changes only through a signed contract change.
If you add an authorized user mid-life, keep the Base Segment at ECOA 1 and add a J1 or J2 segment carrying ECOA 3. Do not re-designate the primary borrower.
Do not use ECOA 1 as a fallback when your source system cannot tell you the liability structure. An unknown designator should be researched, not defaulted, because a wrong designator misassigns delinquency to a real person.

A file can be structurally valid and still be wrong. These are the cross-field conditions ECOA Code 1 has to satisfy.

Every consumer on the tradeline carries their own ECOA code: the primary in the Base Segment, each associated consumer in their own J1 or J2 segment. An ECOA 1 Base Segment with no associated consumers is the normal, fully consistent shape.
Delinquency reported on an ECOA 1 account attaches to exactly one credit file, so the Account Status, Payment Rating, Payment History Profile and Date of First Delinquency on that record are the whole story for that consumer.
If a J1 or J2 segment exists alongside ECOA 1, that segment should be an authorized user (code 3). Any liability code in the associated segment contradicts the Base Segment's sole-responsibility assertion.
Changing the Base Segment ECOA from 1 to a joint code without simultaneously adding the associated-consumer segment produces an association with no co-signer behind it, which validators reject.