Ninety days as five reversible checkpoints for a marketplace software decision

A marketplace seller software ninety day plan is a set of decision checkpoints, not a normal implementation time or forecast. The buyer sets the working days within each phase. Production stays disabled until one England merchant has evidence for its legal seller, named marketplace account and bounded product-to-order job.

Checkpoint one: define the safe baseline

Buyer-set days: [blank]. Owner: [blank].

Record the seller entity, account authority, in-scope products, identifiers, source system and current procedure. Trace approved product content, stock and price into the account, then map placed, authorised, captured, fulfilled, cancelled, returned, refunded, disputed and settled events.

Attach the exact source, timestamp, acknowledgement and exception owner to each state. GOV.UK online-selling guidance provides current context for seller and ordering information. Consumer counsel must decide its application to the actual offer.

Pause if authority, product ownership or the present source of truth cannot be shown. The accepted manual process remains available while the evidence is repaired.

Checkpoint two: assemble the assurance pack

Buyer-set days: [blank]. Owners: [blank by gate].

Catalogue staff approve descriptions, images and rights. The product-safety owner records traceability, restrictions, alerts and withdrawal. OPSS publishes safety alerts, reports and recalls; use a relevant record as a recheck trigger, never as general approval.

Map total price and optional choices, accessibility, personal data, tracking, account security, marketplace terms, VAT records and supplier exit. HMRC's VAT record guidance separates transaction and adjustment evidence. The accountant and VAT adviser set the actual record boundary.

Each specialist records pass, hold or stop for their field. No programme score can compensate for a failed gate.

Checkpoint three: compare routes and prepare tests

Buyer-set days: [blank]. Decision owner: [blank].

Compare the current manual route, single-account configuration, buyer-built integration, hosted tool and managed service on the same job. Leave suppliers unnamed until exact services and current contracts can be verified. Keep cost, staffing, thresholds and service levels blank.

Create synthetic records for an approved and rejected product change, stock conflict, corrected price, late event, duplicate, cancellation, refund and dispute. Add refused tracking, access removal and an accessible customer task. Define expected output, evidence, owner, stop rule and rollback before execution.

The ICO's final storage and access technologies guidance was updated in April 2026 after DUAA changes. A privacy and PECR adviser must review the exact test instrumentation.

Checkpoint four: run controlled evidence tests

Buyer-set days: [blank]. Test lead: [blank].

Use a non-production account or an expressly authorised test facility. Block live listing, payment and customer-message actions. Capture configuration, input, output, logs, exceptions and reviewer sign-off. A pass applies only to the recorded case and version.

NCSC guidance on using SaaS securely covers least privilege, logging, backups and exercises. Test privilege removal, monitoring, export restore and rollback. Stop if personal data enters the test or the accepted baseline cannot be restored.

Checkpoint five: decide and rehearse exit

Buyer-set days: [blank]. Approver: [blank].

Reconcile every result to its predeclared evidence and blank buyer threshold. Record unknowns rather than converting them to passes. Rehearse disabling writes, revoking credentials, restoring product and stock records, handing back open exceptions and recovering exported evidence.

The final verdict is retain current method, investigate further, pass a bounded configuration, hold or stop. Publish no claim of savings, compliance or readiness. Re-open every official source and marketplace record before approval, and set an expiry for the decision pack.