Methodology
How every number on this site is gathered, checked, versioned, and corrected.
Where rates come from
Every rate, slab, and threshold on this site traces back to a specific, dated, cited source — the Income Tax Ordinance 2001, a Finance Act, an FBR notification or SRO, or (for provincial taxes) the relevant provincial revenue authority. We link to that source directly wherever it's publicly available. See the full list on the sources page.
How rates are versioned
Every rate table is stored as a dated rate set with an effectiveFrom date, an effectiveTo date (or null if it's the currently active one), and a status of either confirmed or provisional. A rate set is never edited in place once its effective period has closed — corrections always create a new, dated entry with a note explaining what changed and why. This means a calculation you ran last year will always reproduce the same result today.
What "provisional" means
Pakistan's fiscal year runs July–June, and the Finance Act governing a new year is sometimes not notified by the time that year begins. When that happens, we carry forward the prior year's confirmed rates as a clearly labelled provisional estimate — with an amber notice directly on the calculator — rather than guessing at what might change. The moment the new Finance Act is published, we update the rate set and log the change on the changelog.
Validation
Every rate set is checked automatically before it ships: it must conform to a strict schema (correct field types, valid rate ranges, required citations), it must not overlap another rate set's effective dates, and it must not leave a gap in coverage. A known-good set of calculation results is pinned in automated tests, so a rate update that accidentally changes a past year's result is caught immediately rather than shipping silently.
Corrections
If you spot a rate that looks wrong, please tell us — include the calculator, the figure you expected, and ideally a link to the official notification. Corrections are logged publicly on the changelog the same way any other rate update is, so nothing is quietly patched without a record.
None of this replaces professional advice. For anything you'll act on financially or legally, confirm with a registered tax practitioner or file directly via IRIS (iris.fbr.gov.pk).