Why sanctions and PEP checks at onboarding go stale, how ongoing monitoring works for marketplace sellers and what to do when an alert arrives.
Most marketplaces screen sellers once. The seller signs up, their name is checked against sanctions and PEP lists, the result is clear, and the seller starts trading. That check is then treated as true for as long as the account exists.
It is not. A screening result describes one moment. The lists change, people's roles change, and a seller who was clear in January can be a match in June. This post explains why one-off checks go stale, how ongoing monitoring works, and how to handle the alerts it produces.
This is general information, not legal advice. For your own screening obligations, see GOV.UK guidance and take professional advice.
Three things change after onboarding:
The lists change. Sanctions designations are added, amended and removed. In the UK, the UK Sanctions List has been the only source for UK sanctions designations since 28 January 2026, and it is updated as designations change. A name that was not on it at signup can be added later.
People's positions change. A politically exposed person (PEP) is someone in a prominent public role, or closely connected to one. People are elected, appointed and promoted. A seller can become a PEP, or become connected to one, long after onboarding.
Your sellers change. A company seller can appoint new directors or change owners. The person you screened may no longer be the person in control.
None of this is visible if you only check once.
There are two broad ways to keep screening current.
Periodic re-screening. You re-check every seller on a schedule, say annually, or more often for higher-risk sellers. This is simple, but it leaves gaps. A seller added to a list the day after their annual check stays unnoticed for almost a year.
Continuous monitoring. Each seller is enrolled once, re-screened automatically on a short cycle, and you are only told when something new appears. The gap shrinks from months to about a day, and your team sees changes rather than repeat results.
For sellers you depend on, sellers who receive payouts, or sellers in higher-risk categories, continuous monitoring is usually the better fit.
TrustVerify's ongoing monitoring, available on selected plans, is built around a few deliberate design choices. The monitoring API reference has the detail.
Enrol once, re-screen daily. You enrol a subject with POST /api/v1/aml/monitor, passing your own reference, the name and, ideally, date of birth and country. TrustVerify screens them straight away and then re-screens them every day.
A real baseline, or no monitor. The first screen is the baseline the daily checks compare against. If that first screen cannot be completed, no monitor is created and you get an error. That avoids a monitor with an unknown starting point, which would report every existing listing as "new".
Only new matches alert. When a daily re-screen finds a match that was not there before, it is delivered once as an aml.hit webhook event. A changed caption or score on an existing match does not trigger a repeat alert.
Monitoring you can check. Listing your monitors shows when each subject was last screened and how many re-screens in a row have failed. You can verify monitoring is running, rather than taking it on trust.
Suspension is visible. If monitoring stops for a subject, for example because the account plan has lapsed, you are told with the aml.monitor.suspended event. A suspended monitor keeps its record so it can resume.
Adding a date of birth matters more than it looks. Without it, a common name can match the same unrelated list entry every day.
An alert is a possible match, not a conclusion. A simple handling process:
Write this down before the first alert. A reviewer on a Friday afternoon should not be making it up. Our post on designing a fraud review queue covers how to route these cases without building a backlog. [Planned URL, live on publication.]
You do not have to monitor everyone. A proportionate approach for many marketplaces:
When a seller leaves the platform, stop monitoring them. Keeping a monitor on someone you no longer have a relationship with is hard to justify under data protection principles. [Planned URL, live on publication.]
Monitoring is only useful if alerts reach someone who can act. In practice:
aml.hit to a review case and a payout hold in your own system.aml.monitor.suspended to an alert for your compliance owner, because silence after suspension is not the same as clear.Treating monitoring as a box ticked. Enrolling sellers is the start. Someone has to own the alerts and check that monitoring is still running.
Enrolling without dates of birth. It produces repeat noise on common names and trains reviewers to dismiss alerts.
No plan for a real match. The first confirmed match is the worst time to decide who does what.
Never removing anyone. Stop monitoring sellers who have left, and record when and why.
Ignoring company changes. If a company seller appoints a new director, the new person needs screening too. Monitoring the old director does not cover them.
If you only remember a few points from this post, make them these:
None of these points requires a large team or a long project. Most can be put in place in a few weeks, and each one makes the next decision easier to explain.
Re-screening starts from a good first check: see our KYC software for UK businesses and the guide to choosing KYC software in the UK.
See how ongoing monitoring fits alongside onboarding checks. Explore TrustVerify ongoing monitoring.
KYC, KYB, AML screening and fraud prevention in one place, with published pricing.
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