Studio PonchioSTP
INPS contributions: from 16 September, late payment costs 8.15 per cent a year and an instalment arrangement 4.65
INPS circular 11 September 2026, No 98, aligns civil penalties and interest on instalment arrangements with the new rate on the main refinancing operations of the Eurosystem, which has risen from 2.40 to 2.65 per cent. Consequently, the cost of voluntary correction within one hundred and twenty days, which coincides with that rate, also increases; repayment schedules already notified remain unchanged.
From 16 September 2026, the civil penalty for failure to pay or late payment of social security and welfare contributions is 8.15 per cent at an annual rate, and the interest on instalment arrangements and on deferral of the payment deadline is 4.65 per cent at an annual rate, with the effective dates set out below. This is provided by INPS circular 11 September 2026, No 98, which implements the European Central Bank’s monetary policy decision of 10 September: the rate on the main refinancing operations of the Eurosystem — which has replaced the official reference rate since 2005 — has been raised by twenty-five basis points to 2.65 per cent.
This change affects the cost of labour, but it does not concern only employers. Article 116(8) of Law No 388 of 23 December 2000 applies to anyone who fails to pay contributions or premiums to the compulsory social security and welfare schemes: the same measures apply to the artisan and the trader on the flat-rate and percentage contributions of the self-employed scheme, to the member of the Gestione separata (the INPS scheme for self-employed professionals and certain collaborators) and to the principal required to pay the collaborator’s contribution.
Why the European Central Bank rate determines the penalty
The law does not set a fixed percentage: it sets a formula. Article 116(8)(a) sets the penalty for failure to pay at a rate “equal to the official reference rate increased by 5.5 points”. The interest on instalment arrangements, on the other hand, arises from Article 13(1) of Decree-Law No 402 of 29 July 1981, which constructs it as the sum of a base rate — originally the interbank agreement rate, now, by virtue of subsequent ministerial determinations, the rate on the main refinancing operations — and a surcharge determined by law: originally five points; six under Article 3(4) of Decree-Law No 318 of 14 June 1996; and two, today, under Article 14(1) of Decree-Law No 38 of 27 March 2026, effective from 28 March 2026. This is why an instalment arrangement submitted today costs 4.65 per cent instead of the 4.40 per cent in force until 15 September: if the six-point surcharge had remained, the same rate would produce 8.65 per cent.
The civil penalty is neither a discretionary penalty clause nor a negotiable item: it accrues by operation of law solely by virtue of the delay, without any need for a notice, and, according to the case law of the Court of Cassation, it cannot be reduced on equitable grounds by the court under Article 1384 of the Civil Code, because it is not a contractual penalty clause but a statutory pre-quantification of the loss caused by the delay. The only possible reductions are those specifically provided for by law, which are discussed below.
Failure to pay: 8.15 per cent, and the one hundred and twenty-day window
Failure to pay or late payment of contributions whose amount is already ascertainable from the contribution returns or mandatory records costs, from 16 September, 8.15 per cent at an annual rate — 2.65 plus 5.5 points — with a cap of 40 per cent of the unpaid amount.
Alongside this rule, another applies, introducing a voluntary correction for contributions, not to be confused with voluntary correction in tax matters. From 1 September 2024, by virtue of Article 30(1)(a) of Decree-Law No 19 of 2 March 2024, the 5.5-point surcharge does not apply if payment is made within one hundred and twenty days of the legal deadline, in a single payment and voluntarily, before any notices or requests from the levying bodies. The penalty then remains at the reference rate alone, 2.65 per cent: just under one third. The three conditions are cumulative, and the most fragile is the last, because a request from the Institute closes the window; “in a single payment” must also be taken literally, because a partial payment does not preserve the benefit.
A calculation rule that the circular does not state but which governs every computation: the civil penalty, unlike the interest on instalment arrangements, accrues on the days of delay at the rate in force in each period. For a delay that began before 16 September, 7.90 per cent applies to the days up to 15 September and 8.15 per cent to the subsequent days; a single rate for the entire period is not correct.
Contribution evasion: 30 per cent, and the ways out
The regime changes when the failure to pay arises from omitted or untruthful mandatory records, contribution returns or declarations, with the specific intention of not paying by concealing employment relationships, remuneration or income, or facts or information relevant to the determination of the contribution obligation. Article 116(8)(b) then provides for a penalty of 30 per cent at an annual rate, with a cap of 60 per cent: a fixed rate, which does not depend on the reference rate and which therefore has not changed.
The law provides two ways out, both conditional on voluntary disclosure of the outstanding liability, before any notices or requests from the levying bodies and within twelve months of the payment deadline. The first is not new, as it predates the changes in force since 1 September 2024: the penalty is reduced to the failure-to-pay rate, 8.15 per cent, if payment is made in a single payment within thirty days of the disclosure. The second was introduced by Decree-Law No 19/2024: within the longer period of ninety days, the penalty is reduced to 10.15 per cent. In both cases, the cap is no longer 60 per cent but 40 per cent. Where payment by instalments is permitted, the reduced rate is conditional on payment of the first instalment, and failure to pay, insufficient payment or late payment of a subsequent instalment restores the penalty to the full amount.
Outside the voluntary disclosure scheme, the same decree added Article 116(8)(b-bis), which the circular does not address: where liabilities are identified ex officio or in the course of an inspection, the penalty in the first sentence of Article 116(8)(a) and (b) applies at 50 per cent if the contributions are paid in a single payment within thirty days of service of the notice of assessment. On the failure-to-pay side, this is, from 16 September, 4.075 per cent at an annual rate; on the contribution evasion side, 15 per cent — measures that the circular does not specify, since they derive from applying 50 per cent to the rate set in that first sentence. Here too payment by instalments is permitted, conditional on payment of the first instalment, and here too failure to pay, insufficient payment or late payment of a subsequent instalment restores the penalty to the full amount; for instalments, Article 116(8)(b-bis) refers to Article 2(11) of Decree-Law No 338/1989, so interest on the instalment arrangement also runs on the deferred debt. The 40 per cent cap in Article 116(8)(a) is not halved, however: the reduction affects the annual rate of the penalty, not the ceiling on the total amount due. The point, however, is not settled by the wording, because that cap sits in the same first sentence to which the reduction refers.
Instalment arrangements and deferral of the payment deadline: the date of the application is what matters
Instalment arrangements and deferral of the payment deadline are two distinct legal mechanisms. An instalment arrangement — under Article 2(11) and (11-bis) of Decree-Law No 338 of 9 October 1989 — spreads the payment of a debt that has already fallen due, consisting of contributions and civil penalties already accrued, on which interest on instalment arrangements then accrues; deferral of the payment deadline simply postpones the ordinary payment deadline and only interest accrues.
The 4.65 per cent rate applies to instalment arrangements submitted from 16 September 2026, while repayment schedules already issued and notified on the basis of the previous rate remain unchanged. For deferral of the payment deadline, the new rate also takes effect from 16 September and applies from the contribution relating to August 2026.
The two special reductions
Article 116(10) concerns failure to pay resulting from objective uncertainties connected with conflicting judicial or administrative interpretations as to the existence of the obligation, which is then recognised in judicial or administrative proceedings: if payment is made within the deadline set by the levying bodies, only the legal interest under Article 1284 of the Civil Code is due, at the rate of the first paragraph — for 2026, 1.60 per cent, redefined each year by decree. It operates after the event and is not a route that the person liable can take at the time of payment.
Debts in insolvency proceedings, on the other hand, follow Article 1(220) of Law No 662 of 23 December 1996 — preserved by paragraph 16 of the same Article 116 — which allows the levying bodies to reduce the additional sums — another name for civil penalties — down to a rate no lower than the legal interest rate. INPS exercised this power with the Board of Directors’ resolution No 1 of 8 January 2002, which does not set two percentages but a criterion: the refinancing rate for failure to pay, the same rate plus two points for contribution evasion, with a floor of the legal interest rate. Today, this translates into 2.65 and 4.65 per cent — the latter coincides with the interest on instalment arrangements purely by arithmetic coincidence — and applies only if and when contributions and expenses have been paid in full.
In practice: what to do now
Three checks, in order. First: if there are uncovered periods, determine the days of delay, because within one hundred and twenty days, and subject to the three conditions indicated, the cost falls from 8.15 to 2.65 per cent. Second: anyone about to apply for an instalment arrangement should be aware that it is the date of submission of the application that sets the rate for the entire plan. Third: if a plan is already under way, the rate remains the one notified and there is nothing to recalculate; however, the obligation to pay the instalments on the due dates remains. In the event of an audit, it is useful to keep the payment receipt and any evidence documenting the absence of earlier notices or requests: it is on these elements that the benefit depends.
Frequently asked questions
I will pay the August contributions fifteen days late: how much does it cost?
The ordinary deadline was 16 September 2026, so the entire delay falls after the rate change. If payment is made voluntarily, in a single payment and before any notice or request from the Institute, the civil penalty is calculated at 2.65 per cent, without the 5.5-point surcharge, because payment is made within one hundred and twenty days of the legal deadline. The rate is annual and the calculation follows the actual days of delay: you do not pay 2.65 per cent of the amount, but the corresponding portion for the period, and it is the Institute that calculates the amount on the basis of the contribution return data; the result can be found in the Cassetto previdenziale. If a request had already been received, the rate would revert to 8.15 per cent.
I have an instalment arrangement under way: will my instalment increase?
No, not as a result of this circular. Repayment schedules already issued and notified on the basis of the previously applicable interest rate are not modified: the 4.65 per cent rate concerns instalment arrangements submitted from 16 September 2026 onwards.
After an inspection report, can I halve the penalty by paying in instalments?
Yes. The halving provided for by Article 116(8)(b-bis) is also allowed where payment is made by instalments: in that case its application is conditional on payment of the first instalment, and failure to pay, insufficient payment or late payment of a subsequent instalment restores the penalty to the full amount set in the first sentence of Article 116(8)(a) and (b). Watch the deadline: the thirty days from service of the notice of assessment — not from the date of the report — are referred by the provision to payment in a single payment, whereas for instalments the text merely requires payment of the first instalment. It is a point to check with the Institute before setting up the plan.
Sources
INPS, circular 11 September 2026, No 98, «Variazione della misura dell’interesse di dilazione e di differimento e delle somme aggiuntive per omesso o ritardato versamento dei contributi previdenziali e assistenziali»; INPS, circular 16 June 2026, No 64 (previous measures)
European Central Bank, monetary policy decision of 10 September 2026: rate on the main refinancing operations at 2.65 per cent, effective 16 September 2026; Banca d’Italia, official rates of Eurosystem operations
Law No 388 of 23 December 2000, Article 116, paragraph 8, letters (a), (b) and (b-bis), and paragraphs 10, 15 and 16, as in force on 17 September 2026 (Normattiva)
Decree-Law No 19 of 2 March 2024, Article 30(1) and (2), converted with amendments by Law No 56 of 29 April 2024 (amendments in force from 1 September 2024); INPS, circular 4 October 2024, No 90
Decree-Law No 402 of 29 July 1981, Article 13(1), converted with amendments by Law No 537 of 26 September 1981; Decree-Law No 318 of 14 June 1996, Article 3(4), converted with amendments by Law No 402 of 29 July 1996 (provision still in force, but superseded in the determination of the surcharge)
Decree-Law No 38 of 27 March 2026, Article 14(1), converted with amendments by Law No 88 of 22 May 2026 (Gazzetta Ufficiale No 72 of 27 March 2026; in force from 28 March 2026); INPS, circular 2 April 2026, No 39
Decree-Law No 338 of 9 October 1989, Article 2(11) and (11-bis), converted with amendments by Law No 389 of 7 December 1989
Law No 662 of 23 December 1996, Article 1(220); INPS, Board of Directors’ resolution No 1 of 8 January 2002, Annex No 2 to INPS circular 9 May 2002, No 88, paragraph 5
Civil Code, Articles 1284 and 1384; Ministry of Economy and Finance, decree of 10 December 2025, «Determinazione del saggio degli interessi legali per l’anno 2026» (Gazzetta Ufficiale Serie generale No 289 of 13 December 2025); INPS, circular 30 December 2025, No 157
Ministry of Economy and Finance, decree of 26 September 2005, «Rideterminazione del tasso di interesse da applicare ai tesorieri e cassieri degli enti ed organismi pubblici sottoposti al regime di tesoreria unica» (Gazzetta Ufficiale No 236 of 10 October 2005), relied on by INPS as the basis for replacing the official reference rate with the rate on the main refinancing operations of the Eurosystem
However, the values indicated here are those in force on the date of publication and vary with every change in the reference rate, just as the legal rate is redefined each year by decree: before relying on them, it must be verified that they have not changed in the meantime. This article sets out the criterion; it does not replace the calculation, which the Institute performs on the basis of the contribution return data, and the conditions for voluntary correction must be checked case by case, because the absence of any one of them restores the penalty to the full amount. The same measures also apply, by express provision of Article 116, to insurance premiums; INAIL gives effect to those measures through its own acts. The classification as contribution evasion, and in particular the proof of the specific intention required by Article 116(8)(b), is the point on which much of the litigation focuses: it must be examined on the individual report, not presumed from the mere omission of a contribution return. As for insolvency proceedings, after the Codice della crisi d’impresa e dell’insolvenza, not all crisis resolution procedures are insolvency proceedings: the negotiated settlement procedure (composizione negoziata), for example, is not. Finally, this article does not deal with the further grounds for reduction in Article 116(15), which require an assessment by the levying body, or the limitation period for contribution claims, which follows its own rules and must be verified before any payment for past periods. Before setting up an instalment arrangement, a late payment or a voluntary disclosure, it is advisable to review the position with your own adviser.
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