Forgot to claim a deduction on your tax return? Here is what you can do.

It happens more often than people think. A receipt turns up after lodgement, a course fee is remembered in October, or nobody asked whether you paid for your own uniform. The return was accepted, the refund arrived and the missed item sat there. The good news is that a lodged return is not final until the amendment window closes.

The first step is working out whether the item was actually deductible in that year and whether it can be substantiated. That is a registered tax agent's job, not yours. They compare what was claimed against what could have been for someone in your line of work, ask you about the gaps and tell you what evidence would support each one. If the missed item holds up, they prepare an amendment for you to approve.

If it does not hold up, you are told why. Some expenses feel deductible but are not and some are but only in part. Finding that out costs nothing. A fee applies only where an amendment is lodged and results in an additional refund and it is quoted in writing first.

The deductions people most often forget

Costs of doing the job that did not come through the payroll: union and professional membership fees, licences and registrations you renewed yourself, protective clothing and its laundering, tools and equipment bought out of pocket and the work portion of a phone and internet plan.

Working from home is the other big one. The method used decides what can be claimed and what records are needed and the rules have changed more than once. A return prepared on last year's habits can quietly use the wrong method, or miss the hours entirely.

Then there are the year-specific items: self-education tied to your current job, a change of employer, a period of leave, or the first year of a side income that brought its own deductions with it.

What if I have no receipt?

Substantiation rules apply to every claim, but a receipt is not the only form of evidence and the rules differ by expense type and amount. Bank and card statements, invoices, membership renewals and employer letters all count for something. The agent tells you what is enough. What they will not do is lodge a claim that cannot be supported.

How to get it looked at

Tell us the income years you have lodged and what you do for work. A registered tax agent in the Untax network contacts you, confirms their registration and, with your authority, reviews the return. You get the finding in writing either way.

General information only. It does not take account of your circumstances and is not tax advice. Untax is a marketing and referral service and is not a registered tax agent.