Under the old timetable, VAT for MTD was from 1 April 2019 for all VAT registered businesses (including companies). We had plenty of warnings that companies were included in the guidance.
Under the new timetable, VAT for MTD is from 1 April 2019 for all VAT registered businesses above the VAT threshold. I assume that the definition of businesses is the VAT one and not the income tax one. However assumption is a dangerous thing but I can't see a definitive answer from HMRC or ICAEW etc.
We have a few companies who have bespoke accounting systems due to their industry or international connections. Less than 18 months, is don't long to change systems.