We get asked this often enough that it's worth answering plainly. There is no point at which books become unrecoverable. There is only a point at which recovering them costs more than the owner expected, and that number is driven less by how many months have passed than by how much source documentation still exists.
Time behind matters less than record quality
Two years behind with complete bank statements and an intact receipt trail is a straightforward, if lengthy, job. Six months behind with missing statements, a closed payment processor account, and receipts that lived only in a phone that got replaced is harder, despite being a quarter of the elapsed time.
What actually drives the cost of catch-up work:
- Whether bank and credit card statements are all obtainable
- How many accounts and payment processors are involved
- Whether receipts and vendor invoices still exist in some form
- Whether someone previously coded transactions badly, which has to be unpicked
- Whether the business changed structure or software partway through
Why bulk-fixing doesn't work
The temptation with a large backlog is to force the ending balance to match and move on. It produces a file that looks reconciled and is useless, you cannot build a budget on it, you cannot trust any margin figure it produces, and if the filing is ever examined the working doesn't hold up.
Proper catch-up work runs period by period, in order, so each month closes against an opening position that was itself verified. It's slower. It's also the only version that leaves you with books you can actually use afterwards.
The part people get wrong
Most owners delay catch-up because they assume it's a conversation about how they got behind. It isn't. Getting behind is the single most common thing that happens to a growing business's books, it's a symptom of the business outgrowing the person doing the bookkeeping in evenings and weekends, which is a good problem wearing a bad disguise.
The practical advice: start the assessment before a filing deadline is forcing it. The work is identical, the cost is usually lower, and nobody is making decisions under time pressure.