This is the total amount of VAT you charged on sales to customers. You must also include the VAT you need to pay to HM Revenue & Customs (HMRC) for certain other supplies that you have made, such as:
Take away from this total any credit notes you have issued or debit notes you have received and enter the result in Box 1.
You need to work out the VAT due - but not yet paid by you - on goods that you buy from other EU countries, and any services directly related to those goods (such as delivery charges). Put the figure in Box 2. You may be able to reclaim this amount, and if so remember to include this figure in your total in Box 4.
This is the total of box 1 and box 2 added together. It is the amount of VAT that is due to HMRC.
When you complete your return online, this figure is worked out automatically for you, based on the information you put in boxes 1 and 2. You must not enter the total VAT due figure into box 3 or any other box on your online return.
This is the VAT you have been charged on your purchases for use in your business. You should also include:
Deduct from this total:
The result is the total VAT you can claim back from HMRC.
When you complete your return online, the figure for this box is worked out automatically for you based on the information in boxes 3 and 4. If the amount in box 3 is more than the figure in box 4, you pay the amount in box 5 to HMRC. If the amount in box 3 is less than the figure in box 4, you reclaim the amount in box 5 from HMRC. If the amount in box 5 is zero, you have no VAT to pay or reclaim, but you must still submit your return.
HM Revenue & Customs