The WHAT dimension – goods or services? Rules can be different if selling cross-border.
The HOW dimension – what is the general treatment for the goods or services? Standard rated, zero rated, exempt etc?
The WHERE dimension – UK, EU or outside EU? Vat treatment and process may change.
The WHO dimension – B2B or B2C? Yup, you guessed it…
The WHEN dimension – timing of invoicing, supply and choice of VAT scheme all impact on when VAT should be declared on a return.
And finally our old favourite, the WTF dimension – when all the above rules get thrown away for specific exceptions.