I have recently taken on a client who is a sole director sole shareholder ltd company. They have already passed their first year end (April 20) but no payroll has been set up. Can I register them for PAYE as of April 19, when the company was incorporated, and run a retrospective payroll? They would be paid below the secondary threshold so there would be no tax liability. Is this likely to be more trouble than it's worth as far as HMRC are concerned? I don't think any penalties would be issued as there would be no tax liabilty, but don't want to raise any red flags with HMRC. Thanks in advance for any advice which will be gratefully received.