The VAT helpline did not believe me but I filed a VAT return through my ASA. It may have been because the client deregistered for VAT.
The deregistration date was 31/12 but the return period came up as 30/12 so my software wouldn't let me file since it only deals with returns ending in month ends.
However there was the option on the ASA to file the VAT return, so I put the figures in the boxes in the old way (albeit not MTD).
Anyway the guy on the VAT helpline said he would refer this since he didn't know this was possible....