API Reference
Penalties & Interest
Calculate late-filing fines, remittance default penalties, and commercial interest rates under Nigerian Tax Acts.
Penalties & Interest
POST /api/v1/tax/penalties
Computes statutory default penalties, late-filing fines, and accrued interest under the Central Bank of Nigeria (CBN) Monetary Policy Rate (MPR + 5% commercial spread) for delayed remittances of PAYE, VAT, CIT, or WHT.
Required scope: tax:calculate.
Request Parameters
| Parameter | Type | Required | Default | Description |
|---|---|---|---|---|
principal_amount | number | Yes | — | Unremitted tax balance. Alias: amount. |
due_date | string | Yes | — | Statutory due date in YYYY-MM-DD format. |
target_tax | string | No | "vat" | Tax category: "paye", "vat", "cit", "wht". Alias: specific_tax. |
payment_date | string | No | Today | Actual or planned payment settlement date (YYYY-MM-DD). |
is_late_filing | boolean | No | true | Whether the tax return was also submitted late (incurring filing fines in addition to payment interest). |
Code Examples
curl -X POST "https://taxnigeria.ng/api/v1/tax/penalties" \
-H "Authorization: Bearer txn_your_api_key_here" \
-H "Content-Type: application/json" \
-d '{
"principal_amount": 4500000,
"target_tax": "paye",
"due_date": "2026-01-10",
"payment_date": "2026-04-10",
"is_late_filing": true
}'Response Example (200 OK)
{
"ok": true,
"data": {
"tax_type": "penalties",
"target_tax": "paye",
"principal_amount": 4500000,
"statutory_remittance_penalty": 450000,
"statutory_filing_fine": 50000,
"penalty_amount": 500000,
"interest_amount": 345205,
"total_liability": 5345205,
"days_overdue": 90,
"spoken_summary": "For an unremitted PAYE liability of ₦4,500,000 overdue by 90 days, statutory default penalties equal ₦500,000 (10% penalty plus filing fine) and accrued commercial interest equals ₦345,205, bringing the total amount due to ₦5,345,205."
},
"meta": {
"calculation_id": "calc_pen_2b84e190",
"timestamp": "2026-10-28T13:34:00.000Z",
"latency_ms": 10
}
}