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Errors in a 730 return already filed: how to correct them, and by when

An expense left out, a dependant claimed by mistake, income omitted: after filing, the Italian 730 return can still be corrected, but which route to take depends on who benefits from the correction. If the outcome favours the taxpayer, a supplementary 730 must be filed by 26 October 2026; if it is unfavourable, the correction has to go through the Redditi return — as a corrective return by 2 November, or as a supplementary return at any time up to 31 December 2031.

A 730 return that has already been filed can be corrected even after the 30 September 2026 deadline, but not always with another 730. If the correction produces a larger credit or a smaller amount payable, or leaves the tax unchanged, a supplementary 730 (730 integrativo) must be filed through a tax assistance centre (CAF) or a qualified professional by Monday 26 October 2026. If, on the other hand, the error reduced the tax due, for example because income was omitted or a tax credit was not due, the 730 is no longer enough: the Redditi Persone fisiche return is required, either as a corrective return by Monday 2 November 2026 or as a supplementary return until 31 December 2031, with payment of the tax and of reduced penalties. A single rule separates the two routes: who the correction benefits.

The 2026 deadlines

The deadline for filing the 730, whether pre-filled or ordinary, is 30 September of the year following the income year. It is set by Article 13(1) of Decree No 164 of the Minister of Finance of 31 May 1999, the regulation on tax assistance, as amended by Article 16-bis of Decree-Law No 124 of 26 October 2019; for a pre-filled return filed directly by the taxpayer, Article 4(3) of Legislative Decree No 175 of 21 November 2014 refers to it. Legislative Decree No 1 of 8 January 2024 does not affect this deadline: it amended the deadline for the Redditi return, setting it at 31 October.

After 30 September, this year’s calendar is as follows. The supplementary 730 must be filed by 25 October, under Article 14 of Decree No 164 of 1999; since 25 October 2026 falls on a Sunday, the deadline moves to Monday 26 October, as the instructions to the 730/2026 form expressly state. The Redditi return must be filed electronically by 31 October, which this year is a Saturday followed by the Sunday public holiday of 1 November: the deadline is therefore Monday 2 November 2026. Lastly, a supplementary Redditi return can be filed until 31 December of the fifth year following that of filing, that is, for returns filed in 2026, until 31 December 2031.

The supplementary 730: only when the correction is favourable

The supplementary 730, governed by Article 14 of Decree No 164 of 1999, is used to correct errors or omissions where the correction results in a larger refund or a smaller amount payable, or does not affect the tax. Typical cases are forgotten medical expenses, mortgage interest not reported, or a dependant for whom the tax credit was not claimed although it was due. If the correction increases the tax, the supplementary 730 is not allowed. According to the guidance published by the Revenue Agency on the pre-filled return website, it is not allowed either where the 730 filed showed an amount payable in substitute taxes to be paid with an F24 form.

A supplementary 730 must be filed through a CAF or a qualified professional, even where the original 730 was submitted to the withholding agent or filed directly as a pre-filled return; the one exception is where the withholding agent has refused to carry out that settlement, as described below. The expense documents must be produced; if the original 730 had been prepared by the withholding agent, all the documentation must be produced, not only the additional items.

The front page must show a code. Code 1 is for corrections resulting in a larger credit, a smaller amount payable or unchanged tax. Code 2 is used only to correct the details of the withholding agent who will settle the outcome of the return through the payslip (conguaglio), for example when the taxpayer changed employer after filing. Code 3 combines the two cases. For code 2 there is an additional channel, which the Revenue Agency documents on its own pre-filled return pages and not in the instructions to the form: where the withholding agent notifies the Agency that it refuses to carry out the settlement and the taxpayer is informed of that refusal, a type 2 supplementary 730 may be filed directly through the pre-filled return web application by 10 November 2026.

The supplementary 730 does not suspend the settlements arising from the original 730, which continue as normal. As for the larger credit, Article 19(3) of Decree No 164 of 1999 provides that the withholding agent refunds it with the December salary; taxpayers without a withholding agent receive the refund directly from the Revenue Agency.

Taxpayers who filed the pre-filled return themselves

Taxpayers who filed the pre-filled return on their own could cancel it only once, until 22 June 2026. That option is no longer available. Three routes remain to correct the return: the supplementary 730, through a CAF or a professional by 26 October, if the outcome is favourable; the corrective Redditi return by 2 November, prepared by the Revenue Agency’s web application from the data of the last return filed; after that date, the supplementary Redditi return, until 31 December 2031.

When the correction is unfavourable: the Redditi return

If the error led to paying less than was due, the correction must necessarily go through the Redditi Persone fisiche 2026 return. This happens where income was omitted, for example income shown by a second Certificazione Unica (the annual certificate of income paid and tax withheld, issued by the payer), rent from a lease or miscellaneous income, or where a tax credit or deduction was claimed that was not due. There are two routes, and the difference is first of all a matter of date.

Up to 2 November 2026 the taxpayer files a corrective return within the deadline: a new, complete return with the relevant box ticked. According to Revenue Agency Circular No 42/E of 12 October 2016, in this case the penalty for an inaccurate return does not apply, because the corrected return replaces the previous one within the statutory deadline. The additional tax remains due, together with statutory interest accruing day by day and the penalty for late payment, reduced through ravvedimento operoso (voluntary correction with reduced penalties); interest and penalty are calculated from the payment deadline applicable to taxpayers filing the Redditi return. The corrective return within the deadline has no statutory basis of its own: it is a long-standing feature of the Revenue Agency’s administrative practice, governed by the forms themselves.

After 2 November 2026 the taxpayer files a supplementary return under Article 2(8) of Presidential Decree No 322 of 22 July 1998. It may be filed up to the assessment deadline laid down by Article 43 of Presidential Decree No 600 of 29 September 1973, that is, by 31 December 2031. The credit from the original 730 is still refunded by the withholding agent; the additional tax is paid directly with an F24 form.

Penalties after the 2024 reform

For violations committed from 1 September 2024, the penalty levels introduced by Legislative Decree No 87 of 14 June 2024 apply. An error in a 2026 730 return that reduced the tax due therefore falls under the new regime.

An inaccurate return is punished under Article 1(2) of Legislative Decree No 471 of 18 December 1997 with a penalty of 70 per cent of the additional tax, subject to a minimum of EUR 150. Paragraph 2-bis of the same article, however, sets a lower level: the penalty for failure to pay or late payment, doubled. Since Article 13(1) of Decree No 471 of 1997 sets that penalty at 25 per cent of the amount not paid, an inaccuracy emerging from a supplementary return carries a penalty of 50 per cent of the additional tax. It applies where the inaccuracy emerges from a supplementary return filed no later than the assessment deadline and, in any event, before the taxpayer has formal knowledge of an on-site visit, an inspection, an audit or the start of any administrative assessment activity.

Penalties are reduced through ravvedimento operoso, governed by Article 13 of Legislative Decree No 472 of 18 December 1997: to one ninth if errors made in the return are regularised within ninety days of the filing deadline, to one eighth within the deadline for the return relating to the year in which the violation was committed, and to one seventh after that deadline. The reductions are smaller where the taxpayer comes forward after the tax authorities have acted, and each has its own precondition: one sixth of the minimum after the Revenue Agency has served the draft assessment provided for by Article 6-bis(3) of the Taxpayers’ Charter, where it was not preceded by an audit report; one fifth of the minimum after the violation has been recorded in an audit report, provided the draft assessment has not yet been served; one quarter of the minimum after a draft assessment relating to a violation already recorded in an audit report. In the first and third cases the reduction applies only if no request for assessment by agreement has been filed; in the second, only if no notice of acceptance of the audit report has been sent under Article 5-quater of Legislative Decree No 218 of 19 June 1997: these are points b-ter, b-quater and b-quinquies of paragraph 1 of the same Article 13. Tax, reduced penalty and interest are paid together.

The Revenue Agency’s only comprehensive guidance remains Circular No 42/E of 2016, which predates the reform. For a corrective return within the deadline, the penalty and interest on the unpaid tax run from the Redditi payment deadline, which also measures the ravvedimento reduction. For a supplementary return, what counts is instead 2 November 2026, the Redditi filing deadline. One filed within the following ninety days, up to 1 February 2027, is not an inaccurate return: the original return is on time but irregular. What then applies is the penalty on the content of the return or, where the error shows up on processing, only the penalty for failure to pay — in each case on top of the tax due. Beyond ninety days the penalty for an inaccurate return applies, which for the circular absorbs the penalty on payment. Until the Revenue Agency takes a position on the new regime, the calculation should be prudent.

Favourable corrections after 26 October: the Redditi route

Taxpayers who discover a forgotten expense after 26 October do not lose the benefit. They can file the corrective Redditi return by 2 November or, after that, the supplementary Redditi return until 31 December 2031. Article 2(8-bis) of Decree No 322 of 1998 governs the use of the resulting credit. Where the supplementary return is filed by the deadline for the following year’s return, the credit can be offset under the ordinary rules. Where it is filed later, the credit can be offset only against amounts falling due from the tax period after the one in which the supplementary return is filed, and it must be reported in the return for that tax period. In any event, as the instructions to the forms specify, a refund may still be requested.

The same paragraph 8-bis preserves the right to rely, even during an assessment or in court proceedings, on errors of fact or law that led to declaring a taxable base or tax higher than was due.

From 2027 the references change, not the substance

From 1 January 2027 two consolidated acts apply. Article 367 of the consolidated act on tax compliance and assessment (Legislative Decree No 141 of 5 August 2026) repeals Article 43 of Decree No 600 of 1973, whose time limits move to Article 293; Article 1 of Decree No 175 of 2014, which becomes Article 66 on the pre-filled return; and paragraphs 1 and 3 to 7 of Article 4 of the same decree, which become Article 68 on accepting and amending the pre-filled return. That same Article 367 ties the repeals to the entry into force of the consolidated act, while Article 368 defers its application to 1 January 2027, so that the repeals take effect on that same date; references to the repealed provisions are dealt with by paragraph 3 of Article 367, which treats them as references to the corresponding provisions of the consolidated act.

Decree No 322 of 1998 and Decree No 164 of 1999 remain in force, but for different reasons: as to the former, Article 75 provides that its provisions continue to apply; the latter is not repealed, and it is Articles 66 and 68 that continue to refer to it. The consolidated act on tax penalties (Legislative Decree No 173 of 5 November 2024) repeals Decree No 471 of 1997 and most of No 472: the inaccurate return moves to Article 27, the penalty for failure to pay to Article 38 and ravvedimento to Article 14, at unchanged levels. Anyone correcting the 2026 730 from 2027 onwards will have to cite the new provisions.

In practice

First of all, establish the direction of the error. If the correction increases the refund or reduces the amount payable, the simplest route is the supplementary 730 with code 1, to be filed through a CAF or a professional by Monday 26 October 2026, with the expense documents. If the correction increases the tax, the Redditi return is needed: by 2 November as a corrective return, afterwards as a supplementary return, with payment of tax, interest and reduced penalties.

Taxpayers who changed employer after filing, or who no longer have one, should use code 2; if they receive the Agency’s notice that the withholding agent has refused the settlement, they may also file the correction directly through the pre-filled return web application by 10 November. Where the error was made by the person who provided the tax assistance, it should be reported to them immediately, so that they can prepare a rectifying 730 (730 rettificativo): for the CAF and the qualified professional the legal basis is Article 39(1)(a) of Legislative Decree No 241 of 9 July 1997, which, where a compliance certificate proves inaccurate, allows them to file a rectifying return until the inaccuracy has been challenged by the notice provided for in Article 26(3-ter) of Decree No 164 of 1999; for the withholding agent the same possibility rests only on the instructions to the form.

Taxpayers who, when correcting the return, realise that the second payment on account withheld from their salary will be too high can ask the withholding agent in writing to reduce it or not to withhold it; the 10 October deadline under Article 19(6) of Decree No 164 of 1999 moves this year to Monday 12 October, because the 10th falls on a Saturday.

Lastly, the documentation: expense receipts, the settlement statement of the supplementary 730 and the F24 forms used for the ravvedimento, showing the payment code (codice tributo) and the reference year, must be kept at least until 31 December 2031, and longer if a supplementary return is filed or if a check is under way for that tax year.

Frequently asked questions

I forgot some medical expenses in the 730 I have already filed: can I still recover them?

Yes. A supplementary 730 with code 1 may be filed through a CAF or a qualified professional up to Monday 26 October 2026, even where the original 730 was a pre-filled return filed by the taxpayer; the larger credit is refunded by the withholding agent in December or, where there is no withholding agent, by the Revenue Agency. After that date the Redditi return is used, as a corrective return by 2 November or as a supplementary return until 31 December 2031, with the credit refunded or offset.

I claimed a tax credit for a child who did not qualify as a dependant: can I use the supplementary 730?

No. The correction increases the tax, and the supplementary 730 is allowed only for favourable or neutral corrections. The Redditi Persone fisiche return is required: by 2 November 2026 as a corrective return within the deadline, which according to Revenue Agency practice avoids the penalty for an inaccurate return and involves only the reduced penalty for late payment; afterwards, as a supplementary return with ravvedimento operoso.

Can I still cancel the pre-filled return I filed myself?

No. Cancellation was allowed only once, until 22 June 2026. Three routes remain today: the supplementary 730 through an intermediary by 26 October 2026, if the outcome is favourable; the corrective Redditi return by 2 November 2026; and, after that date, the supplementary Redditi return.

Sources

Articles 13, 14, 16 and 19 of Decree No 164 of the Minister of Finance of 31 May 1999, text in force on 23 September 2026 (Normattiva).

Article 16-bis of Decree-Law No 124 of 26 October 2019, converted with amendments by Law No 157 of 19 December 2019.

Article 39(1)(a) of Legislative Decree No 241 of 9 July 1997, text in force from 12 August 2026, and Article 26(3-ter) of Decree No 164 of the Minister of Finance of 31 May 1999 (rectifying return filed by the CAF or the qualified professional).

Article 1 and Article 4(1) and (3) to (7) of Legislative Decree No 175 of 21 November 2014, in force until 31 December 2026 (repealed by Article 367(1)(fff) of Legislative Decree No 141 of 2026 and transposed, respectively, into Articles 66 and 68 of the consolidated act).

Article 2(1), (7), (8), (8-bis) and (9) of Presidential Decree No 322 of 22 July 1998, text in force on 23 September 2026.

Article 11 of Legislative Decree No 1 of 8 January 2024.

Article 43 of Presidential Decree No 600 of 29 September 1973, in force until 31 December 2026 (from 2027, Article 293 of the consolidated act approved by Legislative Decree No 141 of 2026).

Article 7(1)(h) and (2)(l) of Decree-Law No 70 of 13 May 2011, converted with amendments by Law No 106 of 12 July 2011, on the postponement of deadlines falling on a Saturday or public holiday; paragraph 2(l) is repealed from 1 January 2027 by Article 367 of Legislative Decree No 141 of 2026.

Article 1(2) and (2-bis) and Article 13 of Legislative Decree No 471 of 18 December 1997; Article 13 of Legislative Decree No 472 of 18 December 1997, and Article 5-quater of Legislative Decree No 218 of 19 June 1997, texts in force on 23 September 2026.

Article 6-bis(3) of Law No 212 of 27 July 2000 (Taxpayers’ Charter).

Article 5(1) of Legislative Decree No 87 of 14 June 2024, on the effective date of the new penalties.

Articles 66, 68, 75, 293, 367 and 368 of the consolidated act on tax compliance and assessment, approved by Legislative Decree No 141 of 5 August 2026, applicable from 1 January 2027.

Articles 14, 27, 38, 101 and 102 of the consolidated act on administrative and criminal tax penalties, approved by Legislative Decree No 173 of 5 November 2024, applicable from 1 January 2027.

Revenue Agency, instructions to the 730/2026 form (updated on 28 May 2026) and instructions to the Redditi Persone fisiche 2026 return, booklet 1.

Revenue Agency, measure of 27 February 2026, ref. No 71552/2026, approving the 730/2026 form.

Revenue Agency, Circular No 42/E of 12 October 2016, sections 2.2.1, 2.2.2, 3.1.1 and 4.1.

Revenue Agency, institutional pages on the 2026 pre-filled return: deadlines, cancellation of a filed 730, type 2 supplementary 730.