Got some advice from the content community:
> I don't think we have a style on this - it doesn't really come up on
> GOV.UK mainstream.
>
> In your example, I'd go with something like 'less than £250 before
> VAT' or 'less than £250 (not including VAT)' to make it as clear as
> possible. Would that work?
I’ve gone with ’less than £250 (before VAT)’. I noticed that elsewhere
we’ve said ‘Each message costs 1.58 pence (plus VAT)’ so that feels
fairly consistent.
So that you don’t have to use the footer navigation to switch between
these related pages. Matches the template we use for organising
features-related content.