CT1 Corporation Tax Workings Excel - Free Template

1. Start on CT1_Workings and enter the company name, CRO number, tax reference number and accounting period dates. Then type the accounting profit before tax from your draft accounts.
2. Fill in the add-backs and deductions line by line. Put non-deductible expenses and depreciation in the add-back columns, then enter capital allowances and trading losses brought forward in the deduction columns.
3. Check the taxable profit or loss result. The sheet carries the corporation tax rate and the liability calculation forward for you.
4. Enter preliminary tax paid once you know what has already been paid to Revenue. The workbook will show the balance due or repayment.
5. Review CT1_Summary before you file. Use it as your clean working paper for director approval, notes and final checks.
6. Use the Instructions sheet if you want a quick reminder of the filing sequence and the figures to pull from the accounts.

A CT1 workings sheet is for the people who have to turn draft accounts into a tax computation before the Form CT1 goes to Revenue. In practice that is usually a bookkeeper in a small limited company, an external accountant doing year end, or a director who wants to understand the tax bill before money leaves the bank.

The workbook is useful when the accounting period has ended and you need to separate accounting profit from taxable profit. A company with €180,000 profit before tax, €12,000 of entertainment disallowed and €38,000 of capital allowances needs a clear trail, not a blank notebook.

At year end and before the filing deadline

The pressure point is usually year end and the months leading into the Form CT1 filing. If the company has already paid preliminary tax, you need the balance quickly so the director can decide whether to hold cash back or clear the liability.

A small company example

Take a plumbing company with 4 employees and €420,000 turnover. If accounting profit is €96,000, add-backs are €8,500 and capital allowances are €21,000, the taxable profit drops to €83,500 before the 12.5% rate is applied. That is exactly the kind of working a spreadsheet is better at than a calculator and a pile of notes.

For an Irish trading company, corporation tax on trading income is 12.5%. If the company has €80,000 taxable trading profit, the corporation tax liability is €10,000 before preliminary tax is set against it.

Revenue expects the numbers to be supported by records kept for 6 years, and the company should be able to show where each add-back or deduction came from. Depreciation is not a tax deduction, so you add it back in the computation and then claim capital allowances separately where the asset qualifies.

What belongs in the working

The sheet helps you keep the accounting treatment and tax treatment apart. For example, €6,000 of depreciation on a van is added back, while qualifying wear and tear capital allowances may be claimed at 12.5% a year over 8 years on the tax side.

How the filing ties in

The completed figures feed the Form CT1 filed through ROS. A limited company registered with the CRO uses the company tax reference details on the working paper, and the resulting balance or repayment tells you whether the preliminary tax paid was enough for the period.

The common failure is mixing up accounting profit and taxable profit. If you forget to add back €14,000 of disallowed expenses, you understate the tax bill by €1,750 at 12.5%, and that error follows you straight into the return.

Another problem is treating depreciation as if it were a tax deduction. A company can have a healthy profit and still report the wrong taxable figure if the bookkeeper leaves depreciation in the computation and forgets to claim the qualifying capital allowances instead.

Losses and payments cause trouble too

Trading losses brought forward are often entered without checking the opening figure from the previous period. If you claim €50,000 of losses when only €32,000 is available, the tax computation is wrong and the company may end up with an unexpected balance due later.

Preliminary tax is another place where firms trip up. A company that paid €8,000 on account against a €10,500 liability still owes €2,500, and if nobody spots that before filing, cash flow takes the hit at the worst possible time.

The cost of a messy working paper

Messy CT1 workings usually cost time first and money second. I have seen a one-hour review turn into a half-day rebuild because the figures were spread across emails, a spreadsheet and a PDF draft with no notes column and no clear link back to the accounts.

The same problem shows up in indirect tax, where a VAT3 workings sheet keeps the figures, notes and source links together before the return is filed.

The best way to keep this spreadsheet alive is to link it to the year-end close, not to treat it as a separate job. If you always open it when the draft accounts land, the tax computation is ready while the numbers are still fresh.

Three habits that keep it moving

• Copy the prior period tab and overwrite the figures, so company details and layout stay consistent.
• Use the same folder as the accounts, tax comp and ROS draft so you are not hunting across drives.
• Review the summary sheet before the director signs off, especially when preliminary tax has already been paid.

A simple 30-minute check at the end of the accounts process is usually enough for a small company with one trading activity. Once you are dealing with multiple trades, group relief, or a full tax provision across several entities, the spreadsheet starts to feel too loose and you should move the workflow into accounting software or a dedicated tax system.