Closing the Books Without Surprises: The Checklist Before Corporate Tax

Closing the fiscal year isn’t something you do by pressing a button on December 31st — it’s a review process that, done properly, keeps corporate tax from springing surprises months later. Returns are generally due within 25 calendar days after the six months following the end of the tax period, but the real closing work starts much earlier, while there’s still room to fix things. This checklist walks through the areas that most often cause discrepancies or last-minute adjustments in small and medium-sized companies.

Reconciliations first: make sure the books tell the truth before touching the tax return

Before calculating anything, you need to confirm the books reflect reality. The first step is matching the VAT reported on the quarterly returns against what’s recorded in the input and output VAT accounts: any discrepancy usually points to invoices booked in the wrong quarter, or simply missed altogether. The same goes for withholding tax returns against the payroll and professional fee expense accounts.

It’s also worth reviewing customer and supplier balances: accounts sitting on a debit balance that should really be a credit (or vice versa) distort the balance sheet, and if left unreclassified can end up netting against the wrong figures. And shareholder and director current accounts (loans, running balances) need to be properly documented — tax authorities scrutinize these closely, and an unexplained balance can be read as disguised remuneration.

Depreciation and accruals: the adjustments that almost always get missed

Depreciation on fixed assets needs to be booked before closing, not worked out by hand on the tax return. Go through each asset’s record: acquisition date, depreciable value, rate applied, and the actual number of months in use during the year (an asset bought in October isn’t depreciated as if it had been in service all year). If any asset was disposed of or sold, make sure both the write-off and the resulting gain or loss are properly reflected.

Accruals are the other big blind spot: an annual insurance premium paid in November that also covers the first months of the following year, or rent collected in advance, need to be split across periods so the expense or income lands in the year it actually belongs to. Skipping these adjustments isn’t a minor slip — it inflates or deflates the accounting result, which is the starting point for calculating corporate tax.

Bank reconciliation and the right sequence: balance sheet, then tax return, then close

No reconciliation can be trusted if the bank accounts aren’t matched: every bank statement needs to tie out, entry by entry, with the corresponding ledger balance. The usual culprits — outstanding checks, transfers in transit, unrecorded bank fees — need to be identified and corrected before signing off on the balance sheet, because an unreconciled bank account contaminates everything downstream: cash position, results, and with them, the taxable base.

Once the books are reconciled, the sequence that avoids rework kicks in: first close the balance sheet and profit and loss account with all the above adjustments folded in; then calculate corporate tax based on that already-correct accounting result, applying the relevant extra-accounting adjustments (permanent and temporary differences, offsetting prior losses, reserves); and only then book the corporate tax expense and post the year-end closing entry. Reversing this order — say, calculating the tax return before the bank is reconciled — almost always means redoing the calculation once an adjustment shows up that changes the result.

At Zythos Business we guide sole traders and small companies through this closing process with the same discipline we apply to our own accounts: we check reconciliations, depreciation and bank matching before touching the tax calculation, so the return gets filed on books that already balance — not ones patched up afterward.