December is a strange month for small business finances. It is often one of the busiest trading months of the year. Holiday spending, year-end promotions, and seasonal demand all accelerate. And yet it is also the month when you most need to slow down and look at your numbers, because what you do in December determines how smooth or painful your next tax filing season will be.
The SPT Tahunan filing window opens in January for corporate entities and the deadline is April 30. For individual taxpayers running a business under their NPWP, the window opens in January and the deadline is March 31. Either way, by the time filing starts, you want your full-year books to already be clean. Not "mostly there" and not "I'll sort it in February." Clean.
This checklist covers what to do before December 31 closes. Some items take an hour. Some take a day. All of them are easier to handle now than they are in the middle of filing season.
Complete and reconcile your books through November
Before you tackle December, make sure the previous eleven months are finished. Pull your bank statements for January through November and confirm that every transaction has been categorized. Any months where the bank statement total does not match your bookkeeping records need to be reconciled before you add a twelfth month on top of unresolved differences.
Common gaps that surface at this stage: cash transactions that were never logged, supplier invoices that were paid but not recorded, platform settlements from GoFood or Tokopedia that arrived but were logged as the wrong amount. Go through each discrepancy and resolve it. An unexplained difference of Rp 500 ribu that has been sitting there since April should be found and explained now, not when you are under filing deadline pressure in March.
Count and value your inventory
For product-based businesses, whether a clothing shop, a grocery warung, or a cafe with significant stock, you need a physical inventory count as of December 31. This count becomes part of your year-end balance sheet, and it is the starting inventory for your 2026 cost-of-goods calculation.
Write down what you have and what it cost you to acquire, not what you think you could sell it for. Inventory is valued at cost (harga pokok) for accounting and tax purposes. Items that are clearly unsellable, expired food products, damaged goods, obsolete stock, may be written down to zero. If you are carrying significant obsolete inventory, now is the time to recognize that rather than letting it inflate your reported assets.
For food businesses with perishable inventory, the count needs to happen close to December 31. Do it on the last working day of the month or the morning of January 2 using December 31 as the reference date. Your POS system's inventory module, if you have one, should provide a close approximation, but a physical spot-check on high-value or high-cost items is worth doing.
Collect outstanding Bukti Potong and invoices
If your business received payments from clients or counterparties who withheld PPh 23 on fees paid to you, you should have received a Bukti Potong PPh 23 for each withholding. These documents show the amount withheld and paid to DJP on your behalf, and you need them to credit that amount against your annual tax liability.
December is a good time to chase down any Bukti Potong that have not arrived yet. Many companies issue them at year-end, and the last week of December is when administrative processes slow down. If you are owed certificates from counterparties who regularly withhold from your invoices, send a reminder now. Getting them in January instead of December is manageable. Getting them in March when you are trying to file is a genuine problem.
Similarly, if you have unpaid invoices from customers that you intend to write off as uncollectible, the decision and documentation for those write-offs should be completed before December 31.
Confirm your PPh 25 installment payments for the year
PPh 25 is the monthly income tax installment that businesses pay in advance throughout the year. The amount is based on the prior year's tax liability. At year-end, you should have a record of every PPh 25 payment made, with the payment date and SSP reference number for each.
These payments reduce your final tax liability when you file. If you have twelve months of installment payments properly documented, the annual filing is partly a matter of confirming that the installments already paid cover or approach what you actually owe. If you missed one or more months, you may have additional liability plus interest to address in the filing.
Review your asset register for any additions or disposals
Any equipment or fixed assets purchased during the year need to be added to your asset register with the purchase date, cost, and applicable depreciation category. Any assets disposed of, sold, scrapped, or stolen should be removed with the disposal date and, if applicable, any proceeds received.
This matters for the balance sheet reported in your SPT and for the depreciation expense you will claim for the year. Depreciation that you fail to calculate and claim is a lost deduction. Assets that remain on your register after disposal overstate your assets and may create inconsistencies the DJP's data systems flag when they cross-reference your filings against prior years.
Estimate your tax liability before you file
By mid-December, you have enough data to make a reasonable estimate of your annual tax position. What was your gross income for the year? What are your deductible expenses? What is your estimated net taxable income? Apply the applicable tax rate or norma to get an estimated liability. Subtract the PPh 25 installments already paid. The difference is what you will either owe or have overpaid when you file.
Knowing this number before January has practical value. If you owe a significant amount, you can begin setting it aside now rather than facing a large cash outflow in March. If you appear to have overpaid through installments, that may affect your cash flow planning for the first quarter of the coming year.
This is also the right moment to confirm that your books and your bank balance are consistent. The closing bank balance on December 31 plus receivables minus payables should be roughly consistent with the financial picture your income and expense records reflect. If they are not, there is a reconciliation problem that requires attention before filing.
The businesses that enter SPT filing season with clean books, a complete inventory count, a full set of Bukti Potong, and a reasonable estimate of what they owe are the ones that file on time without errors. The businesses that enter it with unreconciled books and missing documents are the ones calling their accountant in a panic in the last week of March. December is when you choose which one you are going to be.