Identify what is overdue
List each return and period that is outstanding. Company accounts, corporation tax and VAT are related but different obligations. A reminder may refer to only one of them, so do not assume completing one task will automatically resolve the others.
Rebuild the records needed
Gather the records for the affected periods and note where information is missing. Bank statements, sales records, invoices and previous accounts can help reconstruct the picture. Keep later periods organised too, so the backlog does not continue to grow.
Prepare returns in a workable order
The order of work depends on how the figures connect. Accounts may need to be prepared before a company tax return can be completed. Discuss the sequence and the information you must supply before assuming a submission date.
Your questions, answered.
Can I file if records are incomplete?
Incomplete records need to be reviewed and gaps addressed. Do not invent figures simply to submit something.
What if more than one year is late?
Prepare a list of periods and documents available for each. The work can then be considered as a sequence.
Is a late personal tax return covered here?
No. Personal Self Assessment catch-up work has its own page under personal tax.