IS installments: calendar and calculation 2026

Update of April 5, 2026 - Corporate tax advance payments represent one of the first tax cash outflow items for subject companies. In 2026, a company subject to IS must pay four quarterly installments, each calculated on the basis of the reference tax for the previous financial year. Failure to comply with the schedule or a calculation error exposes you to surcharges and late penalties.

Instalments of IS are due by all companies liable to corporate tax whose turnover excluding tax for the previous financial year exceeds 2.3 million euros. Each installment represents 24% of the reference IS amount, divided into four equal payments. The electronic payment schedule imposes specific deadlines, generally the 15th of the third, sixth, ninth and twelfth month of the current financial year.

An IS deposit is an advance payment of corporate tax. The mechanism is provided for by article 1668 of the General Tax Code (CGI). The idea is simple: the State does not want to wait for the end of the financial year and the submission of the tax return to collect part of the tax. Advance payments allow tax revenue to be smoothed throughout the year.

The calculation is based on a reference: the corporate tax due for the financial year preceding the current one. This reference tax serves as the basis for calculating each installment. The rate applied is 24% of this reference tax, divided into four equal payments.

To complete, see Taxation and declarations: VAT, IS, advance payments, Tax package submission deadline 2026 and Taxation and company taxes.

All companies subject to IS are not required to pay advance payments. The trigger threshold is set by article 1668 of the CGI.

The turnover threshold

The obligation to pay advances applies to companies whose turnover excluding tax for the previous financial year exceeds 2.3 million euros. This threshold is assessed at the level of each company, not at the group level. A subsidiary whose turnover remains below this threshold is not liable for advance payments, even if the parent company pays them.

Newly created companies

Companies created during the current financial year are not subject to the obligation to make advance payments for their first financial year. In fact, they do not have any previous reference exercise. This exemption ceases from the second financial year, if the turnover threshold is reached.

Corporate groups

Each company in the group is assessed individually with regard to the threshold of 2.3 million euros. There is no CA consolidation mechanism to determine the down payment obligation. A holding company whose only income comes from dividends from its subsidiaries does not necessarily reach the threshold, because dividends do not constitute turnover in the tax sense of the term.

The schedule of installments is set by article 1668 of the CGI and the administrative doctrine of the DGFiP. For the financial years ending December 31, the four deadlines are as follows:

First installment: March 15, 2026

The first payment occurs during the third month of the financial year. For a financial year aligned with the calendar year, the deadline falls on March 15, 2026. This first payment is often the most difficult to anticipate, because it occurs before the company even has a clear vision of its results during the year.

Second installment: June 15, 2026

The second payment is due June 15, 2026. On this date, the company generally has the results for the closed financial year and can begin to adjust its forecasts for the current year.

Third installment: September 15, 2026

The third installment is due on September 15, 2026. It is often at this deadline that companies notice a gap between the deposits paid and the actual expected result.

Fourth installment: December 15, 2026

The final installment is due December 15, 2026. It closes the advance payment cycle. The balance of IS will be paid when the tax package is submitted, generally in May 2027 for financial years ending December 31.

Exercises not aligned with the calendar year

For companies whose financial year does not coincide with the calendar year, the due dates are shifted accordingly. Installments are due on the 15th of the third, sixth, ninth and twelfth month of each financial year. It is essential to recalculate these dates as soon as a change in closing date occurs.

The calculation of advance payments is based on a precise mechanism defined by article 1668 of the CGI.

The basic formula

The total amount of advance payments is equal to 24% of the corporate tax due for the previous financial year. This total is then divided into four equal payments.

Amount of each deposit = (IT of the previous financial year × 24%) ÷ 4

Concrete example

Let's take a SAS whose corporate tax due for the 2025 financial year amounts to 50,000 euros. The calculation is as follows:

• Total amount of deposits: 50,000 × 24% = 12,000 euros
• Amount of each deposit: 12,000 ÷ 4 = 3,000 euros The company will have to pay 3,000 euros on each of the four deadlines in 2026.

The case of the reduced IS rate

SMEs whose turnover excluding taxes is less than 10 million euros and whose capital is at least 75% held by individuals benefit from the reduced corporate tax rate of 15% on the fraction of profit not exceeding 42,500 euros (article 219-I-b of the CGI). This reduced rate also applies to the calculation of the reference tax serving as a basis for advance payments.

The impact of social contribution on profits

The social contribution of 3.3% on IS (article 235 ter ZC of the CGI) is included in the calculation of the reference tax. It therefore enters into the 24% base used to calculate advance payments.

The law provides for adjustment mechanisms to prevent advance payments from becoming disproportionate to the actual result.

The ability to modulate downwards

Article 1668-V of the CGI allows the company to modulate downwards the amount of its advance payments when it estimates that its result during the financial year will be lower than that of the previous financial year. This modulation must be justified by objective elements: drop in activity, exceptional loss, change in structure.

Modulation is carried out directly during electronic payment on the impots.gouv.fr portal. The company declares an amount lower than the automatic calculation. Please note: if the modulation proves to be unjustified, the administration may apply an increase of 5% on the difference between the deposit which should have been paid and the deposit actually paid.

The capping of deposits

The total amount of advance payments cannot exceed the amount of corporate tax actually due for the current financial year. If the advances paid exceed the final tax, the excess is chargeable to the IS of the following financial years or, failing that, refundable. This capping mechanism is provided for by article 1668-III of the CGI.

Additional deposits

In certain cases, the company may be required to pay additional deposits. This is particularly the case when it has exercised an option for a different tax regime or when it has carried out an exceptional transaction having a significant impact on its tax result.

Payment of IS installments is made exclusively by telepayment on the professional portal impots.gouv.fr. Payment by check or free transfer is no longer accepted for this tax.

The electronic payment procedure

The company connects to its professional space on impots.gouv.fr using its identifiers. She selects the "Pay" section then "Corporate tax". The system automatically calculates the expected deposit amount. The company can confirm it as is or modify it if it meets the conditions.

Payment must be made no later than the due date. A payment made the same day is considered regular, but it is recommended to anticipate at least two working days to avoid technical hazards.

Late penalties

In the event of late payment, the administration applies an increase of 5% to the amount of the deposit not paid or paid late, in accordance with article 1731 of the CGI. This increase is due automatically, without the administration having to send any prior notice. Late payment interest at the rate of 0.20% per month is added to this increase.

**Our firm's experience reveals several recurring errors in the management of IS deposits.

Forget the turnover threshold

Some companies cross the threshold of 2.3 million euros in turnover without realizing it. The obligation to make advance payments arises automatically as soon as this threshold is exceeded. Ignorance of the threshold does not constitute grounds for exemption.

Neglect modulation

Many companies mechanically pay the four installments without checking whether their current results justify this level of payment. In a context of declining activity, this rigidity can weigh heavily on cash flow.

Confusing installments and IS balance

Deposits do not constitute the final payment of the IS. The balance is calculated when submitting the declaration of results (form no. 2065). If the deposits are insufficient, a supplement is due. If they are excessive, a tax credit is recognized.

Not anticipating structural changes

A merger, a split or a change in closing date modifies the calendar and the calculation of deposits. These operations must be reported to the corporate tax service (SIE) to avoid double taxation or omissions.

Hayot Expertise Advice: An IS deposit is not just a tax line. It's a budgetary signal. Well anticipated, it improves visibility. Poorly followed, it degrades cash flow without warning. We recommend that our clients review the advance payment forecast at each interim closing, not just at closing.

The management of IS deposits must be part of an overall cash flow management approach.

Integrate down payments into the cash flow plan

From the opening of the financial year, the four installment deadlines must be included in the forecast cash flow plan. Each installment must be provisioned monthly to avoid tensions at the time of maturity.

Revise forecasts at each closing

A quarterly or half-yearly statement makes it possible to compare the actual result with the initial forecasts. If the difference is significant, modulation of the remaining installments must be considered. This regular review is the key to effective tax management.

Anticipate the IS balance

The deposits represent only 24% of the IS of the previous financial year. The balance, which can be substantial, occurs when the tax return is submitted. It is prudent to provision monthly the difference between the advances paid and the estimated IS for the current financial year.

We integrate IS installments into a cash flow calendar and tax management consistent with your financial year.

**👉 Manage** your IS deposits with precision

In 2026, corporate tax payments must be read as a component of the financial management of the company, not as an isolated formality. Respecting the schedule, the accuracy of the calculation and the ability to modulate according to the actual result are all levers which protect cash flow and avoid penalties. A company that controls its advance payments controls a significant part of its tax planning.

(Official sources: impots.gouv.fr - IS telepayment, professional tax calendar, declaration of results; General Tax Code articles 1668, 1668-V, 1731, 219-I-b, 235 ter ZC; BOFiP BOI-IS-CHAMP-40-30-10)