Correcting an Italian income tax return: the supplementary return (dichiarazione integrativa)
An error or omission in a return already filed is corrected with a supplementary return (dichiarazione integrativa): you file again the same form for the tax year concerned, online only, ticking the « dichiarazione integrativa » box on the cover page and reporting both the corrected data and all unchanged data. Anyone who sent a 730 and spots an error can file a corrective Redditi return by 2 November 2026, then a supplementary Redditi return by 31 December 2031, i.e. by 31 December of the fifth year after the year of filing. If more tax is due, tax, interest at the legal rate and the penalty reduced under the ravvedimento operoso are paid together; if more credit results, a refund can be requested.
Up to date for 2026 — verified on September 25, 2026Official procedure, no printed formGuide: about 60 min
This content is part of the path: Receiving a notice from the Revenue Agency· Step 7 of 8· Next step: Paying an Italian tax notice (avviso bonario) in instalments with the F24
Deadlines
- 2 November 2026
- Deadline for the corrective Redditi return after a 730 sent in 2026 (31 October falls on a Saturday)
- 31 December 2031
- Deadline for the supplementary Redditi return after a 730 filed in 2026: 31 December of the fifth year after the year of filing
- 1 February 2027
- Deadline for a late Redditi return for individuals, within 90 days of the ordinary 2 November 2026 deadline (31 January falls on a Sunday)
Documents to prepare
- The original return for the year to be corrected, which can be downloaded from the Cassetto fiscale
- That tax year's return form and instructions
- The data to add or correct and, if you received one, the compliance letter with its act code
- The F24 form to pay tax, interest and reduced penalty, if the correction increases the amount due
No form is attached to this procedure: the link leads to the official page that describes it.
What this page gives you
The guide above and the link to the official site. ActioFin does not produce any document for this page: whatever you fill in or file is done on the official medium.
Who this applies to
- Taxpayers who realise they left out data or entered it incorrectly in a return already filed
- Businesses, self-employed workers and individuals who receive a compliance communication from the Agenzia and want to settle the errors it reports
- Anyone who filed a 730 and needs to complete or correct it with a corrective or supplementary Redditi return
- It does not cover those who did not file on time: within 90 days of the deadline they file a late return, not a supplementary one
Worked example
Paolo Neri, employee in Verona, left some income out of his 730
In December 2026 Paolo realises he left 3,000 euro of income out of the 730 he filed in 2026. As 2 November 2026 has passed, he can no longer use the corrective Redditi return: he files online the supplementary Redditi return for tax year 2025, before 31 December 2031, ticking the « dichiarazione integrativa » box on the cover page, with the missing income added and all the data already declared. The new return shows more tax due: at the same time he pays with the F24 the additional tax, interest at the legal rate accruing daily and the reduced penalty, worked out with the ravvedimento-operoso and interessi-legali calculators, putting tax, interest and penalty on separate lines with their own tax codes.
How to fill it in, step by step
- Identify the return to correct and get the form and instructions for the specific tax year in which the error was made, from the Agenzia's « Modelli di dichiarazione » page.
- If you sent a 730, choose the right form: corrective Redditi return until 2 November 2026, supplementary Redditi return afterwards, by 31 December of the fifth year after filing.
- Complete the form ticking the « dichiarazione integrativa » box on the cover page, and report the corrected income or taxable amounts together with all the other data of the original return that do not change.
- Send the return online only, directly or through an authorised intermediary; with the pre-filled return web application only if the first return was also sent with it.
- If more tax or less credit results, pay at the same time with the F24 the tax, interest at the legal rate and the ravvedimento operoso reduced penalty, on separate lines with the specific tax codes.
- If you received a compliance letter, copy into the relevant F24 field the « codice atto » shown at the top left of the letter.
- If instead more credit or less tax results, request any refund due.
Good to know
- For those who received a compliance communication, the Cassetto fiscale generally provides the original return to supplement, sometimes a supplementary return already pre-filled with the reported data, the compilation software and the filing instructions.
- Amounts due after a compliance communication cannot be paid in instalments.
- Interest runs at the annual legal rate from the day payment was due to the day it is made: the interessi-legali calculator works it out.
- Penalties are reduced according to the time elapsed since the breach under the ravvedimento operoso: the reduction fractions are carried by the ravvedimento-operoso calculator, the full penalty for an inaccurate return by the sanzione-dichiarazione-infedele calculator.
- The additional Redditi return (Redditi aggiuntivo) is something else: it is for those who sent the pre-filled 730 and received income to be reported in certain Redditi schedules, for instance RM, RS or RU.
Common mistakes
- Reporting only the corrected data in the supplementary return, forgetting all the other data already shown in the original return.
- Forgetting to tick the « dichiarazione integrativa » box on the cover page.
- Using the current year's form instead of the one for the tax year in which the error was made.
- Filing the supplementary return without paying tax, interest and reduced penalty at the same time when more tax is due.
- Confusing the supplementary return with the late return, which concerns those who did not file on time.
Frequently asked questions
Until when can I correct a return filed in 2026?
After a 730, with the corrective Redditi return until 2 November 2026 and then with the supplementary Redditi return until 31 December 2031, i.e. 31 December of the fifth year after the year of filing.
Can I file the supplementary return on paper?
No: it must be filed online only, directly or through an authorised intermediary.
What must I pay if the correction increases the tax?
At the same time, the tax due, interest at the legal rate accruing daily and the reduced penalty under the ravvedimento operoso, with the F24 form.
What if the correction is in my favour?
If the new return shows more credit or less tax, you can request any refund due.
Can I use the pre-filled return web application for the supplementary return?
Only if the first return was sent with the pre-filled return web application; otherwise use the compilation software or an intermediary.
Go further
Compute the related amounts
Understand this form: the related course
Official sources
- Agenzia delle Entrate — Compliance for businesses and the self-employed: how to settle the errors made — September 25, 2026
- Agenzia delle Entrate — Compliance for individuals: how to settle the errors made — September 25, 2026
- Agenzia delle Entrate, Pre-filled return — Additional, corrective, supplementary and late Redditi returns — September 25, 2026
Guide and document provided for information purposes only; they do not constitute personalised legal or tax advice. Check the recipient organisation's requirements and consult a professional if needed.