Hi, We have noticed that some of our Invoices were inputted without vat and need to change these manually but i am getting an error saying that we cannot delete this payment as we have filed our tax return

Yep. That's correct. You can of course change it, people make mistakes. But, I'm saying you can't just go into an old period and start changing stuff. 1. Bullet wont update your VAT return, 2. You need to rebill your clients etc. etc.
Manual Journal Entries.
Bullet is a full accounting product like Xero. The reason we don't look like Xero and are easy to use is we've built this layer of software on top of the accounting product. That layer of software understands the the accounting rules. We use workflows to extract the right information out of you. We only built workflows for the most common tasks as they're complex to build, nearly a million lines of code in Bullet.
Of course you can bypass any of our workflows by using Manual Journal Entries. But you're into old school accounting then, Debits and Credits. I don't recommend doing anything with them unless you know what you're doing. Bullet won't issue any warning because it's assuming you're an accountant/bookkeeper. If we're having this conversation it's safe to say you're not familiar with them :(

What you need to fix: Accounting & VAT Payment
You have submitted a VAT return for say Jan to Mar - with a total of €1,000. You've now realised the invoices/bills we're wrong. Meaning that the VAT total of €1,000 is now wrong.
So you need to.
Send the clients that you miss billed the correct Invoices, adjusted.
You need to manually submit your new VAT return.
You manually adjust your accounts in Bullet using manual journal entries.
Locked Tax Period
You can unlock tax periods by clicking on the Tax period in the Tax section and click 'mark as unpaid'.
You can then edit what you want. BUT NOTE - Bullet wont update your VAT return & your accounts will be out as your VAT amount hasn't been updated it also wont re-issue adjusted invoices etc.

This needs to be done using journal entries.
Talk to your accountant and they'll advise you.

Thanks Pete

Hmm. When have you to submit the P35?

Sorry your p30 have you submitted it?

Ok. We'll have a look.
Did you setup your employees manually or did you use the P2C file?