What period sales to be reported

Hi Thank all your support. I Applied for UK VAT registration on 10 July 2024 but HMRC sent the VAT Effective date of registration is 1 Sep'2023. My sales UK TO Germany mainly. Should i include my EU sales from Sep'2023, Although my threshold sales exceed the pound 85000 limit in Dec2023. This sale to be reported in UK VAT return or Non Union OSS VAT Return. Please Advise.

Hi, 
Businesses should account for VAT from their effective date of VAT registration onwards.
Please refer to notice 700/1 section 5 regarding starting to account for VAT 5. Accounting for VAT 5.1 Keeping records and charging VAT — when to start  
B2C supplies of digital services where the customer is in an EU member state would normally be accounted for under the non-union OSS return.
The place of supply for B2C digital services is normally where the customer belongs.
The net value of the sale would also be declared in box 6 on a VAT return as per notice 700/12 section 3.7 3. How to fill in each box on your return
Thank you.