MTD VAT applications need to be approved by HMRC prior to use.
Microsoft are currently getting Dynamics Nav versions approved having now (recently) released patches.
Microsoft have only (recently) released MTD VAT related patches as part of the cumulative update program for versions 2015, 2016, 2017 and 2018.
So older versions of Dynamics Nav / Navision will not have a patch released and therefore will never be approved by HMRC.
So older versions of Dynamics Nav / Navision cannot be used for VAT transmissions to HMRC under MTD VAT.
This needs to be completed by your Microsoft partner - they have the tools to complete this work, we do not. So we do not offer this service.
But this will take time to complete and it is unlikely your partner will have available resource to complete this work pre April 2019. The upgrade is not covered by your current maintenance charges though the new licences will be provided free of charge.
So there is a cost involved as well as upheaval while the upgrade takes place.
The time taken to upgrade will depend on how old your version of Navision / Dynamics Nav is and the level / number of bespoke changes you have made to your Navision / Dynamics Nav database re tables, forms, pages, reports and codeunits.
Assuming an upgrade as described under option 1 is not possible in the timescale, your only real option for the April 2019 go live is to use a 3rd party tool.
This will allow you to complete VAT statements in the usual way in Navision / Dynamics Nav, copy / paste / export into Excel and then use the 3rd party tool to submit.
The approved 3rd party tools are listed here. These include full application approvals as well as 3rd party submissionm tools.
The one we like the look of (as it looks like an Excel add on tool so simple) is here.
1. Assess whether MTD VAT applies to your business. If so......
2. Register for MTD VAT - yes this does require registration on top of your existing VAT registration.
3. Pay for the 3rd party tool.
4. Complete the relevant setup data on the 3rd party tool.
6. By April 2020, plan a Dynamics Nav upgrade as the 3rd party tools cannot be used. At least that is the latest thinking by HMRC on the subject but this does change so keep on eye on this web page for the latest news.