Preparing corporate income tax: a checklist for the file
Which documents, reconciliations and considerations belong in the corporate income tax file? 2026 rates, the items corrections come from and a complete file checklist.
The short answer
A corporate income tax file is only complete when three things are right: the annual report has been checked and reconciled, the path from commercial to taxable profit is substantiated per correction, and the choices made are recorded together with the reason. The third is the most neglected and costs the most time the following year.
For 2026 a rate of 19% applies to the first € 200,000 of profit and 25.8% above that. That makes the boundary around € 200,000 a point of attention when planning the return and the provisional assessment.
Rates and timeline
| Item | 2026 |
|---|---|
| First bracket rate | 19% up to and including € 200,000 of profit |
| Second bracket rate | 25.8% above € 200,000 |
| Return for a financial year equal to the calendar year | Before 1 June of the following calendar year; an extension is possible |
| Provisional assessment | During the year, to be adjusted as soon as expectations change |
Check the exact filing and extension dates per year with the Tax Administration, and allow for non-calendar financial years in your planning.
What belongs in the file
Basis
- Adopted or draft annual report with the notes.
- Trial balance and ledger movements for the financial year.
- Reconciliation between the annual report and the books, with no unexplained differences.
- An opening balance sheet that reconciles with last year's closing balance sheet, including tax balance sheet items.
Tax
- Reconciliation from commercial result to taxable result, substantiated per correction.
- A tax balance sheet showing valuations that differ from the commercial balance sheet.
- An overview of loss relief and amounts available from earlier years.
- Participations and the application of the participation exemption.
- Fiscal unity: composition, effective date and intercompany relationships.
Substantiation per item
- Investments with the date they were brought into use, the depreciation method and any investment allowance.
- Provisions with the calculation and the reason the provision is needed.
- Current account relationships with the shareholder, including interest and repayment arrangements.
- Mixed costs and the deduction limit applied.
- Staff costs including the final levy under the work-related costs scheme, see The work-related costs scheme: checks and common mistakes.
Accountability
- Who prepared the return and who reviewed it, with dates.
- A record of choices made and of positions that could be open to discussion.
- A copy of the return as submitted and of the assessments received.
From commercial to taxable result
The reconciliation is the heart of the file. Work with a fixed overview in which every correction is a line with a reference to its substantiation.
| Type of correction | Examples | Point of attention |
|---|---|---|
| Non-deductible or partly deductible costs | Mixed costs, fines, certain entertainment | Check the percentage and threshold per year |
| Deviating depreciation | Restrictions on buildings, accelerated depreciation | Date brought into use and the basis |
| Investment schemes | Small-scale investment allowance, energy and environmental schemes | Registration deadlines and conditions |
| Valuation | Stock, work in progress, provisions | Consistency with last year |
| Participations | Participation exemption, result of a participation | Documentation of the interest held |
| Interest and financing | Interest deduction limits, current account | Whether the terms are at arm's length |
Changes in percentages and thresholds are where old files quietly go out of date. So include explicitly in the review process that the percentages used were checked for the year concerned.
Items most corrections come from
Current account with the shareholder. A growing debt without repayment, no interest or interest that is not at arm's length, and no record of the arrangements.
Investments late in the year. The date brought into use determines the depreciation and sometimes the entitlement to a scheme; an invoice dated December says nothing about when the asset was brought into use.
Provisions that linger. A provision nobody remembers the substantiation for is a point of discussion during an audit.
Work in progress. Differences in valuation between commercial and tax accounts, often without a reconciliation.
Staff and the work-related costs scheme. The final levy declared in the payroll administration but not processed in the annual report, or the other way round.
Choices you record
In almost every file you make choices that nobody can reconstruct next year without a record: which depreciation method was chosen and why, why a provision was valued at this amount, why a cost item was or was not corrected, and which position was taken on an unclear item.
Record three things per choice: the position taken, the reason, and the source or consultation it is based on. That is the same logic as your control trail, see Audit trail.
Provisional assessment and payment
A provisional assessment that does not move with the result creates two problems: unnecessary tax interest if it is too low, and unnecessary pressure on liquidity if it is too high. So build in two fixed moments: an interim test halfway through the year and a test at the last monthly close of the financial year, asking whether the provisional assessment still matches expectations.
That test is only meaningful if the interim figures are reliable, see Setting up the monthly close.
File checklist
- The annual report and the books reconcile, differences explained.
- The opening balance sheet reconciles with last year, including tax items.
- The commercial to taxable reconciliation is complete, every correction substantiated.
- Percentages and thresholds for the relevant year checked.
- Loss relief updated.
- Investments tested for when they were brought into use and for applicable schemes.
- Provisions reassessed and substantiated.
- The current account assessed for arm's length terms and recorded.
- The work-related costs final levy processed and reconciled with the payroll administration.
- Choices and positions recorded with the reason and the date.
- The provisional assessment tested against the expected result.
- Review performed by a second person, with a date.
Handover to next year
Close the file with a short handover note: which items need attention next year, which positions should be reassessed and which questions remained open. That is the cheapest way to avoid starting over next year.
Fiscal unity: extra points of attention
In a fiscal unity for corporate income tax, the results of the subsidiaries are attributed to the parent. Four points that lead to follow-up questions in practice.
Composition and dates. Record which companies joined or left the unity and when. Joining halfway through the year splits the financial year for tax purposes.
Intercompany relationships. Receivables, payables and intercompany transactions must eliminate. A difference in the intercompany current account between two companies is a classic cause of a reconciliation that does not balance.
Losses from before the unity. Pre-unity losses can only be offset to a limited extent and should be tracked separately, per company.
Rate effect. Because the 19% first bracket applies once per taxpayer, choosing a fiscal unity has consequences for the rate. That is a consideration you record with the reason, not a given you carry over from last year.
When to involve a tax specialist
Not every file requires specialist knowledge, but these situations do: a reorganisation or acquisition during the financial year, applying the participation exemption to an unusual interest, interest deduction limits on financing within the group, an innovation box, cross-border activities, and any situation in which you take a position that must be defensible.
In those cases record not only the outcome, but also the question asked and the facts the answer is based on. Advice without the accompanying facts is no longer usable next year.
Five mistakes that make the file expensive
- Reusing last year's percentages in the tax corrections, without checking for changes.
- Not reconciling the opening balance sheet with last year's closing tax balance sheet, so the difference carries forward every year.
- Not recording choices, so a successor cannot explain the treatment.
- Forgetting the work-related costs final levy in the annual report while it was remitted in the payroll return.
- Not adjusting the provisional assessment after a good or bad year, resulting in tax interest or liquidity pressure.
Next step
See how Giroo Tax builds the file from the same data as the bookkeeping, so reconciliations do not have to be reconstructed by hand.
Content reviewed: July 2026. Rates, thresholds and deduction limits change each year and the tax assessment depends on the facts; have positions assessed by a tax specialist.