If you are a vat registered trader that has to pay vat once you issue a vat invoice then you can go for vat cash accounting scheme to delay your vat payments. Under this scheme you will have to pay vat only after your customers have paid against your vat invoice.
Under regular vat accounting, you will need to pay vat in the next vat return regardless of whether your client has cleared payment of the vat invoice. This is especially true in case your business compels that you issue credit invoices most of the time. When this occurs you would end up paying of the vat amounts in case your client fails to make any payment whatsoever. Thus, you would end up paying vat even on the debt.