According to the Guardian, there have been 4 Suspicious Activity Reports sent into the NCA by Bankers over Reform's finances.
Exclusive: Bankers have raised potential money-laundering concerns over loans and donations involving senior party figures
www.theguardian.com
Not just Farage but Tice as well. They aren't a crime report to be clear. I'd be curious what the case is with other Political Parties.
According to the report they are, at least, still trying to find the source of the funds from one of them.