Since the implementation of VAT in UAE, the VAT301 form has been available on e-services portal to manually process the VAT payment on Customs Declarations using the Tax Registration Number (TRN).
Recently, Federal Tax authority (FTA) has communicated with the taxpayers that the VAT301 form will be discontinued shortly for users who have a valid TRN and were using this form earlier for settlements via their VAT returns.
Source: premier-brains.com