Six months. That is the rule behind when a company income tax return is due once a company has settled into a normal filing rhythm, counted from the end of your own accounting year.
The six-month rule, worked from your year end
The Nigeria Tax Administration Act 2025 sets the company income tax filing deadline at six months after the end of the company's accounting year, for a company that has been trading more than 18 months.
For example, a company with a 31 December year end files by the following 30 June. A company with a 31 March year end files by 30 September instead. The rule moves with your own accounting calendar, not one fixed date for every company.
A company still inside its first 18 months of trading works to a different clock. Company income tax in your first year of trading sets out that rule instead.
Filing even in a quiet year
Every taxable person must file a return each year, even if no tax is due. A company that made no profit, or ran at a loss, still owes a return by the same deadline.
Treating a loss-making year as a reason to skip filing is one of the more expensive assumptions a company can make, since the filing duty and the tax actually due are two separate things.
What the self-assessment return includes
The return is a self-assessment, not a form the Nigeria Revenue Service (NRS), formerly FIRS, fills in for you. It brings together your own computation of tax due, your accounts for the year, evidence of tax already paid, and a principal officer's sign-off that the return is accurate.
A company that qualifies as small can attach a simpler statement of accounts instead of a full audit. Our piece on the small-company exemption covers who that is.
Paying in one sum or by instalment
The tax itself does not have to leave your account in one payment. The law allows paying in a single sum or across instalments, as long as the instalments are cleared by the same filing deadline.
Miss that end point, even by instalment, and it is treated the same as paying late. The instalment option spreads the cash outflow. It does not move the deadline.
What happens if the date passes unused
Missing this deadline brings its own fixed penalties, separate from the small-company or first-year rules covered elsewhere on this site. Our piece on the cost of filing CIT late sets out the exact figures.
The shorter deadline if you stop trading
A company that permanently stops trading in Nigeria does not wait for its usual year end to come round. It files within six months of ceasing to trade instead.
Common mistakes
- Filing by calendar year instead of accounting year. The six-month clock starts at your own year end, which may not be 31 December.
- Skipping the return in a loss-making year. The filing duty is separate from whether tax is actually owed.
- Treating instalments as a deadline extension. Every instalment still has to clear by the original filing date.
Once your CIT filing is current, a tax clearance certificate becomes something you can actually request when a tender or bank asks for one. Start a tax clearance certificate request once you know you need it, and read the Nigeria Tax Administration Act explained for how this deadline sits inside the wider law. Keep the date itself on the compliance deadline calendar.