Calculation rules

Interest will be calculated by applying to the amount of the improper deduction the late payment interest rate in force in each of the years included between the expiration date of the declaration period of the year in which the improper deduction was made (or, where applicable, from the day following the date on which the refund was obtained) and the date on which the declaration corresponding to the 2022 financial year is submitted.

The sum of the late payment interest corresponding to each of said years will determine the total amount of late payment interest corresponding to the improper deduction.

In determining default interest, three periods can be distinguished for these purposes:

• Initial period

It will include the number of days that have elapsed since the day following the end of the declaration period corresponding to the year in which the deduction that is now being restored was made (or, where applicable, from the day following the date on which the refund was obtained). and on December 31 of said year.

The determination of the amount of late payment interest corresponding to this period can be carried out using the following calculation formula:

Interest delay initial period = Deduction amount x (interest rate ÷ 100) x (period (number of days) ÷ 365 or 366)

The interest rate will be taken, expressed as a percentage of 100, the default interest rate in force in the year to which the initial period corresponds.

• Intermediate period

It will include each of the full years following the initial period, until December 31, 2022.

The determination of late payment interest corresponding to each of the calendar years included in this period can be carried out using the following formula:

Late interest each year = Deduction amount x (interest rate ÷ 100)

The interest rate, expressed as a percentage of 100, will be the default interest rate in force in each of the years that make up this period.

However, given that the same late payment interest rate was in force in the years 1994, 1995 and 1996 (11 percent), the interest corresponding to those of said years that are part of the intermediate period may be determined globally, multiplying the aforementioned late payment interest rate for the number of said years that make up the aforementioned period. This same rule may be applied in the years 1999 and 2000 for which the same late payment interest rate was in force (5.5 percent); for the years 2002 and 2003 in which the same default interest rate was in force (5.5 percent); for the years 2005 and 2006 in which the same default interest rate was in force (5 percent) and for the years 2008 and 2009 (until March 31, 2009) in which the default interest rate was 7 per 100. From April 1, 2009 to December 31, 2014, the late payment interest rate is 5 percent. The default interest established for the year 2015 was 4.375 percent; for 2016, 2017, 2018, 2019, 2020, 2021 and 2022, 3.75 percent, and for the year 2023, 4.0625 percent.

• Final period

It is the period between January 1, 2023 and the day of presentation of the declaration for fiscal year 2022 (June 30, 2023).

The determination of the interest corresponding to this period can be done using the following formula:

Late interest final period = Deduction amount x (4.0625 ÷100) x (T23 ÷ 365)

T23 represents the number of days of the delay period included in the year 2023, that is, those elapsed between January 1 and the date of submission of the 2022 tax return.

Note: For 2023, the default interest rate of 4.0625 percent approved by the forty-second Additional Provision of Law 31/2022, of December 23, on General State Budgets for 2023 (BOE of December 24)