Hi, I am trying to NETFile HST for a client but getting an error message that reporting period does not match with CRA records. Client claims that the reporting period is correct for the last few years. The client has a refund. I tried calling CRA but due to labour disruptions they are not responding. I don’t have client’s access thru represent a client, it’s pending due to CRA strike. Any suggestions how can file using any other method would be appreciated. Thanks.
Have you asked the client for a previously filed HST return or a letter issued by CRA where they inform the taxpayer of their upcoming HST filing due date? If the client is a sole proprietor and have acess to their CRA MyAccount, they may be able access their CRA MyBusiness account from the CRA. If both options don’t work then the only option would be to call the CRA (not really an option at the moment).
Oh the good old days, I’ve had clients tell me they were “100%” sure that they weren’t missing any tax slips but then I’d find extra slips on RepAClient. 
paperfile is your only option unless you verify the correct period
Thanks to both @BertMulderCGA and @GuyWhoPlaysGolf
To stay on the safe side, I end up sending it through paper mail. Once CRA is back from their strike, we’ll figure it out what is happening with this account. Thanks again.