How import VAT and GST are calculated

Written by James F. Kollie, Jr. · Published 9 September 2026 · Reviewed 9 September 2026 · 8 min read

The base, not the rate, is where costings break

Import VAT and GST are charged on a legally defined taxable value. In most systems that value is built up from the customs value and then increased by the charges the destination country decides belong in the base. Two importers with the same 15% rate can face very different tax bills because one of them is taxed on a base that includes duty, freight and a trade levy.

The common global pattern

taxable base = customs value
             + customs duty
             + any levies or excise the country includes
             (+ certain post-importation costs in some systems)

import VAT / GST = taxable base x tax rate

This pattern is widespread because it follows the logic of a destination-based consumption tax: the tax is meant to fall on the full value of the goods as they enter the domestic market, including the protective charges applied at the border.

Jurisdictions vary, and the variation is material. Differences you should expect to find include:

• Whether the customs value is CIF, or the goods value alone with freight and insurance excluded.
• Whether the customs value is uplifted by a fixed percentage before tax is calculated.
• Which levies, fees and excise amounts sit inside the base and which sit outside it.
• Whether some inland or handling charges incurred before clearance are added to the base.
• Whether the tax is recoverable as input tax, and how quickly, which changes the cash impact but not the amount.
• Whether zero-rating, exemption or a deferment scheme applies to your goods or your business.
• Whether the destination charges a general sales tax on a narrower base, or no import consumption tax at all.

Because of this, TrueCost lets you define the base explicitly: you choose which components — customs value, duty, each levy, each excise line — are switched into the taxable base, rather than accepting one hardcoded assumption.

Worked example

Illustrative rates and base composition only. Verify both for your destination.

Goods                                     40,000.00
Freight                                    3,500.00
Insurance                                    260.00
------------------------------------------------------
CIF                                       43,760.00
Customs value (= CIF)                     43,760.00

Customs duty            @ 12%              5,251.20
Trade levy              @ 0.5% of CIF        218.80
Inspection fee (outside the base)            150.00
------------------------------------------------------
Taxable base = 43,760 + 5,251.20 + 218.80 49,230.00
Import VAT              @ 15%              7,384.50

Note the effect: 15% of the invoice value would have been 6,000. The actual VAT is 7,384.50 — 23% higher, entirely because of how the base is built. Notice too that the inspection fee is excluded here; if the destination included it, the tax would rise again.

What happens if you get the base wrong

Base used                   VAT @ 15%    Error vs correct
Invoice value only           6,000.00       -1,384.50
CIF only                     6,564.00         -820.50
CIF + duty                   7,351.20          -33.30
CIF + duty + levy (correct)  7,384.50               —

On a single container that under-estimate is a rounding annoyance. Across a year of shipments priced from it, it is the difference between a healthy margin and a loss.

How to verify the base for your destination

1. Start with the destination customs or revenue authority's own published guidance on the value for VAT or GST purposes on importation. This is the primary source; a freight forwarder's summary is not.
2. Read the valuation rules alongside it. The customs value definition — and any uplift — determines the first line of the base.
3. List every charge on a recent clearance from that country, then classify each one as inside or outside the base according to that guidance.
4. Ask your licensed clearing agent to confirm your list in writing, and to flag anything product- or origin-specific.
5. Reconcile against the actual assessment notice after clearance. If your calculated tax differs, find the line that explains the gap and correct your base.
6. Record the source and the date you checked. Bases change with budget cycles; a base you verified two years ago is a guess today.

The World Customs Organization's material on customs valuation is a useful primary reference for the valuation concepts most national rules are built on, but only the destination authority can tell you what its own tax base includes.

Related mechanics

• Excise often sits inside the base — see ad valorem versus specific excise methods.
• The duty amount that feeds the base depends on your tariff line — see how HS codes relate to duty rates.
• For destination examples of a base assembled in practice, see importing into Liberia and importing into South Africa.

How we calculate and verify this

Every figure on this page is produced by the same calculation engine the free calculator and TrueCost Pro use, applied in the sequence set out in our calculation methodology. We publish no duty, excise, levy or tax rates of our own: rates, bases and exemptions are entered by you, and country presets are explanatory starting points that record where they came from and when they were last reviewed.

Results are estimates. This guide explains general method, not the law of any country. Confirm your tariff line, rate, tax base and exemptions with the destination customs authority or a licensed clearing agent before you commit to a purchase or a price. Nothing here is customs, tax or legal advice. If you find something wrong, tell us and we will correct it.