You generally need to send a VAT return to HMRC every 3 months. This is called your “accounting period.”
If you are registered for VAT, you must submit a VAT return even if you have no VAT to pay or recover.
The deadline for filing your declaration online is generally one month and 7 days after the end of an accounting year. This is also the deadline for paying HMRC. You must allow time for the payment to reach HMRC's account.
If you miss the deadline for submitting your return, HMRC will send you a 'VAT Notice' telling you how much VAT they think you owe.
You may have to pay a surcharge or penalty if you file your return after the due date or if you pay it late.
The amount you owe will be calculated differently depending on the accounting period it corresponds to.
For each VAT return sent late, you will receive one penalty point. This includes void returns (where you have nothing to declare).
Once you reach your penalty point threshold, you will receive a £200 penalty. The threshold is set by your accounting period (whether you pay monthly, quarterly or annually).
You will receive an additional penalty of £200 for each subsequent late submission while you are at the threshold.
For more information :
https://www.gov.uk/submit-vat-return/late-returns-and-payment