Brexit Britain's under pressure to come up with a swift registration process for EU nationals in the UK.
The European Parliament's Guy Verhofstadt's been meeting Home Office officials in Brussels.
The UK's Windrush scandal - threats to deport some relatives of Caribbean workers - has hiked concerns.
"One application or registration per family has to be sufficient. That has to be possible," said Verhofstadt.
"Secondly, we are also looking that it becomes a real system of registration rather than application. That means that if people fill in all the data that are necessary, from that moment on there is this status. And that is not necessary for weeks or months, not to say years before the Home Office is agreeing with this."