Lodging an overdue tax return with several years of bank statements

31 October is the self-lodgement deadline. If you're behind by more than one year, that date arrives faster than the backlog gets sorted, and the statements are usually where the time actually goes rather than the return itself.

One thing worth knowing before starting: engaging a registered tax agent before 31 October generally moves you onto their client lodgement program, which usually extends the deadline well past October, sometimes into the following May. If the backlog is large enough that October genuinely isn't achievable, that's often the more realistic path than trying to compress several years of records into the time remaining. It doesn't apply automatically in every case, particularly with existing overdue years already on file with the ATO, so it's worth a direct conversation with an agent rather than an assumption.

Working out which years need statements at all is the first real step, and it's simpler than it sounds. Every financial year since your last lodged return needs its own records. If you've lost track of what's actually been lodged, the ATO can confirm which years show as outstanding, which avoids converting statements for a year that turns out not to be needed.

Once the years are known, the statements themselves come from wherever each bank keeps them. Recent history is usually still downloadable from online banking, but most Australian banks only keep a limited window available that way, commonly somewhere between 90 days and two years depending on the bank. Anything older, and any account that's since been closed, has to be requested directly from the bank rather than pulled from an active login. The bank retains the records regardless of whether the account is still open; getting to them just takes an extra step.

Once the PDFs are in hand, batch conversion takes ten at a time and returns one merged CSV per batch, every transaction in date order, with a Source File column on each row. Running one batch per financial year tends to be the tidiest split, since it produces one file per return rather than one large file that needs separating out afterwards. A single account across three overdue years is three batches; two accounts across three years is six.

Transactions come back categorised, which gets a usable first pass at separating income from expenses and spotting the transfers that shouldn't count as either. Every category can be corrected before downloading, so anything the automatic pass gets wrong on an unusual merchant takes a click rather than a rebuild.

If a registered tax agent ends up doing the lodgement, handing them clean CSVs per year instead of a folder of PDFs per account takes the same slow step off their desk, where it's usually billed by the hour regardless of who does it.

Converting statements this way gives you a starting point for the return, not a finished one, and none of the above is tax advice.