p11d-loan-benefit-calculator-using-old-interest-rate-for-25-26-2-25-and-should-be-3-75

P11D- Loan Benefit Calculator using old interest rate for 25/26- 2.25% and should be 3.75%

20th April 2026

In the 2026 tax year on version 26.1 and 26.1.10.60, the P11D Benefit Calculator is still using the old rate of 2.25 when it should be 3.75. Beneficial loan arrangements — HMRC official rates – GOV.UK.

Use this workaround: To use the override % rate and edit the rate. Select ‘Loan benefit calculator’, tick ‘Use own interest rate’ and complete the form eg ‘Loan Outstanding’ box etc .

The IRIS Development team is investigating this, so our apologies if you have the issue and to use the workaround above – also see below under loan benefit screen via edit-employment benefits .

This also applies to the loan benefit screen via edit-employment benefits ensure ‘use benefit value as entered’ and to fill in the manually entry and save it. (Do not use calculated value tick box)

Loan Benefit Calculator guide

The loan calculator will compute the interest due on loans outstanding in the selected fiscal year. The result is shown in the ‘cash equivalent of loan’ area. There is an example below.

1. Enter the loan outstanding at the start of the tax year or the amount borrowed if a new loan in the year.
2. Enter the later of the date the loan was made or the start of the tax year (IRIS automatically inserts the start of the tax year).
3. The rate of interest is inserted automatically depending on the date selected. Other rates of interest may be used.
4. Enter the earlier of the date the loan was fully or partly repaid, or the day before another advance was made, or the day before the interest rate changes or the end of the fiscal year. (IRIS automatically inserts the day before the next interest rate change or the end of the fiscal year, as appropriate.)
5. The loan benefit field shows the interest due on the details entered above. Click the Add loan benefit button to add it to the running total and then click the [4] button to continue the calculation.
6. Continue the calculation from step 1. IRIS will automatically have filled in the details based on the information entered above. The only changes that may be required for the second and subsequent additions are to the loan outstanding and the date ‘to’.

Example

If the loan outstanding at 6/4/98 was £10,000 with £3,000 paid off on 31/12/98, this would be split at follows:

1. £10,000 at 7.25% from 6/4/98 to 31/12/98;
2. £7,000 at 7.25% from 1/1/99 to 5/3/99;
3. £7,000 at 6.25% from 6/3/99 to 5/4/99.

Make the following entries on the loan calculator to achieve this:

4. Enter loan outstanding 10000 (step 1), date ‘to’ 31/12/98 (step 4) and click Add loan benefit then [4] (step 5) to continue.
5. Enter loan outstanding 7000 (step 1) and click Add loan benefit then [4] (step 5) to continue.
6. Click Add loan benefit then [4] (step 5) to finish and the result (£662.45)is shown in the the ‘cash equivalent of loan’ area.