By Isara, Accounting Manager, Kreston Thailand
When I help companies close their year-end accounts, one of the most common problems I encounter is not a major accounting error. It is the fact that nobody in the business fully understands the history behind the numbers anymore.
I see this situation repeatedly in companies where the accounting staff has completely changed over time, or where the business has changed accounting firms multiple times over the years. Each new person tries to continue the work based only on what they can see in the records at that moment, without understanding how previous balances were created, why certain accounting treatments were used, or what unresolved issues already existed before they arrived.
Over time, the accounting records slowly lose continuity.
The real problem is not that the new accountant does not want to do the work properly. It is that they were never given enough history or documentation to understand what happened before.
What Happens When There Is No Proper Handover
In many cases, there was never a proper handover process. Supporting documents from previous years cannot be located. Old reconciliation files are missing. Historical explanations were never documented properly. New accounting staff often do their best to continue the work, but without enough context, accounting treatment gradually changes from one person to another.
Sometimes transactions are recorded incorrectly simply because the person handling them does not know the original logic behind earlier entries. The real problem usually appears during year-end closing.
Why Consistency in Accounting Matters
Another issue I often see in these situations is the lack of consistency in accounting treatment over time.
When accounting staff change frequently, or when different accounting firms take over the work without proper handover, the recording approach gradually changes from one person to another. Some accounts are classified differently each year. Certain reconciliations stop being performed consistently. Supporting schedules may no longer follow the same structure as previous periods.
At first, these changes may seem minor. But over time, inconsistent accounting treatment makes the records much harder for the next person to understand and continue properly.
This is one reason why maintaining consistency in accounting is so important. Good accounting is not only about recording transactions correctly today. It is also about ensuring that the logic, supporting documents, and reconciliation methods remain consistent enough for future staff to follow without needing to reconstruct the entire accounting history again.
Why Year-End Closing Becomes So Difficult
At that stage, we are expected to finalize financial statements within a limited timeframe while simultaneously trying to reconstruct years of missing accounting history. We have to trace old balances, review incomplete reconciliations, search through scattered supporting documents, and piece together fragmented information from multiple sources.
And by then, the transaction volume is often already very large.
This is why year-end accounting cleanup becomes far more complicated than many business owners expect. Once information has been lost over several years, it becomes extremely difficult to recover everything completely. Some documents no longer exist. Some explanations disappeared with employees who already left the company. Some balances continue rolling forward year after year simply because nobody is fully confident enough to clear or adjust them properly anymore.
Most accounting problems do not begin with fraud or major mistakes. They begin when nobody is fully certain whether the existing records are still correct but everyone continues moving forward anyway.
Even with significant effort, there is always a risk that some information remains incomplete.
The Tax Risk That Many Companies Underestimate
The risk is not only operational. It can also create direct tax exposure.
In many year-end engagements, we find that supporting documents can no longer be located for certain expenses. Some transactions were recorded years ago without sufficient evidence, while others were carried forward repeatedly without proper review. Under Thai tax rules, expenses without adequate supporting documentation may become non-deductible expenses for corporate income tax purposes.
As a result, the company may face additional tax costs, penalties, or surcharges later even if the original transaction itself was legitimate.
This is why missing documentation becomes much more serious than many businesses initially realise. The issue is not only whether the accounting entry exists. The issue is whether the company can still support and explain that entry years later when auditors or tax authorities request evidence.
What Good Accounting Support Should Actually Provide
Good accounting support should not only produce financial statements. It should create structure that survives staff turnover and business changes. That means maintaining proper documentation, preserving reconciliation history, and ensuring that accounting treatment remains consistent over time.
In every year-end engagement where we have had to reconstruct missing accounting history, the pattern is usually the same. The issue was never one major mistake. It was years of small gaps that nobody documented, clarified, or followed up.
If you have recently changed accounting providers in Thailand and are concerned about what the previous team left behind, contact us to discuss what a proper accounting review should look like.