How the penalty and interest calculator works
Last updated 10 November 2026
SARS can charge two different amounts when you are late. A fixed administrative penalty applies each month a return is still outstanding. Interest applies to tax that is paid after its due date. This tool works out both from the rules in the Tax Administration Act and the figures SARS publishes.
How it works
- Enter your taxable income for the preceding year, or a negative number for an assessed loss, and the months the return stays outstanding.
- Enter the unpaid tax, the rate, the date it was due and the date you pay.
- Read the monthly penalty, the penalty after those months, the interest and the two added together.
Worked example
With the starting figures:
- Taxable income of R 500 000 or less falls in the “R250 001 to R500 000” band, so the fixed penalty is R 500 a month, R 3 000 after 6 months.
- Interest of R 521.22 builds up on R 20 000 over 92 days at 10.25% a year.
Where the figures come from
The penalty table is section 211 of the Tax Administration Act. The monthly recurrence and the 35-month limit come from the SARS admin penalty page. The prescribed interest rate comes from SARS’s provisional tax guide. We read them on 10 November 2026. The copy of the Act we read is the 2012 publication, so later amendments were not checked. The figures register says what is confirmed.
Who the fixed penalty applies to
The fixed amount penalty applies to a natural person with an outstanding income tax return, as listed in the public notice. It is not the only penalty SARS can impose.
A public notice lists the incidences. For individuals, it is failing to submit an income tax return when one or more returns are outstanding.
How interest is counted
Interest is on the daily balance and compounded monthly (section 187(2)). The Act does not state a day count, so this tool uses days over 365 and adds the interest to the balance at each month end. SARS’s own statement is the final figure.
For income tax the interest starts seven months after a year ending in February, and six months after any other year end (section 187(3)(b)).
Interest also runs on penalties from their payment dates (section 187(3)(d)). This tool does not add it.
What this page does not cover
A percentage-based penalty on unpaid tax can also apply (section 213 of the Act). Its percentage is set in the tax Acts and is not included here.
Penalties for companies and trusts, understatement penalties, and penalties for other kinds of non-compliance are not included. This is an estimate from public rules, not tax advice. Read the full disclaimer.
Things to watch
- SARS’s own notice and statement of account are the final figures.
- The prescribed rate can change. Check the current rate before relying on the estimate.
Related: the tax-year planner and the tax-year countdown.