The issue with private VRMs is that the Euro status (if present) and / or the emissions data may not follow in a timely manner. It might take several weeks for the DVLA to backfill and frequently never backfills at all. Add to this that the TFL database only updates from the DVLA once a month for situations like yours. So your compliant vehicle could well be stuck in nowhere for a month or longer.
You should check
the TFL ULEZ status here for both the current and proposed registrations. Keep screen prints and make sure they show the date.
Beware of third part websites that offer ULEZ checks. Most of them are flawed.
Get a good scan or photocopy of the current V5c.
Check again when the new V5c arrives and get screen prints.
If the previously compliant car is now showing as non-compliant then you should manually register it with TFL.
See here for instructions.You'll need to upload the new V5c and a Certificate of Conformity from the vehicle's manufacturer. Sometimes these are free, eg Porsche and sometimes they are chargeable. That said TFL have been known to accept copies of the old and the new V5c and DVLA VRM transfer confirmation instead, since the old and new V5c should have the same make and model details and the VIN numbers should match.
Once TFL have confirmed that your manual registration is accepted then confirm again on the ULEZ checker.
Don't drive the car in the ULEZ until it shows as exempt on the checker or make sure it is registered on autopay if it isn't and you need to drive it.
Ideally you should also duplicate all of your checks above with the
government CAZ checker. The CAZ zones that are springing up all over the country have variations and are not necessarily the same as ULEZ.
