If you have things on the deduction side that the government doesn't already know about, you can submit a self-assessment or an amendment. Deductions themselves

If you have things on the deduction side that the government doesn't already know about, you can submit a self-assessment or an amendment. Deductions themselves should be simplified. You bring deductions up as if it's a problem but many other countries, like the UK, do it this way without problems. Most people here do not submit tax returns.