can you tax a car this early for next month or are you retaxing from last month ?
on the renewal i got my tax runs out end of this month but it says dont apply before 5th august
That's because they tend to be snowed under with people taxing for THAT month at the beginning of the month, and also it can mean that you lose a month by taxing it twice.
You can tax a car whilst it is already taxed, and the system is quite happy to let you, there is no check to stop this, therefore if you'd have taxed it two weeks ago (5th Aug), it would have started the tax from 1st Aug and would have been a duplicate of the one you already have expiring end of Aug.
If you tax it now, either at a Post Office or online, it shouldn't be a problem. Whenever I do they always arrive within a few days.
Not "displaying" your tax disc is an offence, but if you actually have one, and the system shows that you do, unless it is suspected that you are not showing it for some other reason it is unlikely to cause you any great issue as the paperwork is too great for an offence that the CPS would dump once they saw your vehicle was actually taxed anyway.