When the Instrument Changes, Your History Does Not
A rate change is arithmetic. A change of instrument is a change in what the number *is* — and for a while your warehouse will hold stock costed under both rules at once.
Most tax changes are a number moving. You update a rate, documents raised after the change carry the new figure, and the only real work is making sure nothing straddling the date gets the wrong one. Tedious, bounded, well understood.
Liberia is going through the other kind. Goods and services tax is legislated to be replaced by a value added tax — a single-stage cascading tax giving way to a credit-invoice one. The rate moves too, but the rate is the least interesting part.
Under a cascading GST, tax you pay on a purchase is part of what the purchase cost. It is not recoverable, so it belongs in the cost of the goods and in the price you set from them. Under a VAT, the same payment is a receivable: netted against tax you charge, with only the difference reaching the authority. Same money, same supplier, same invoice — and two entirely different accounting facts.
Confirm the dates with your own adviser, including against this post
The transition has been legislated rather than completed, and the practical positions around it — registration windows, transitional rules, what happens to documents that straddle the date — are exactly the things that move. We are describing the shape of the problem, which does not change, rather than a timetable, which does. Anybody selling you certainty about a transitional detail is selling you their reading of it.
The warehouse will hold both rules at once
This is the part that surprises people, because it is not a compliance problem at all. It is a costing one.
Stock bought before the change was costed with non-recoverable tax inside its unit cost, correctly. Stock bought after the change is costed without it, also correctly. Both sit on the same shelf. If you sell from both in the same month at the same price, your margin moves for a reason that has nothing to do with your buying, your selling or your suppliers.
| Under a cascading tax | Under a credit-invoice tax | |
|---|---|---|
| Tax on a purchase | Part of the cost of the goods | A receivable, netted against tax charged |
| Where it belongs | In unit cost, and therefore in your price | In a tax account, and not in your price |
| Effect on gross margin | Already absorbed | Should never have been absorbed |
| Effect on closing stock | Valued including the tax | Valued excluding it |
| What a weighted average does | Blends the two, and describes neither |
For one costing period your average unit cost is an average of two different rules. It is not wrong by an error — it is wrong by a definition.
Documents on both sides of the line
The second problem is ordinary and still expensive: an order placed before the change and delivered after it, an invoice raised under one instrument and credited under the other, a quotation issued at one rate and accepted at another.
None of that is difficult to reason about one document at a time. What makes it hard is volume and memory: three months later nobody recalls which side of the line a particular order sat on, and the only way to find out is the paperwork.
- For any open order at the cutover: which instrument governs the delivery, and does the record say so or does somebody remember?
- For a credit against an old supply: at which rate, under which instrument, and can your system express that?
- For stock on hand at the cutover: what was in its cost, and can you still identify it a year later?
- For your price list: which of the two rules were the prices built from?
- For your closing stock figure: does it span the change, and did anybody say so in the notes?
Where our own product stops, which is the reason to read the rest
Three of our limitations bite precisely here, and they are in the honesty ledger on the Liberia page rather than being discovered by you in month two. Stating them is not modesty — it is the only way the paragraphs above are worth anything.
Landed cost that stays open after receipt
Costs arriving weeks after the goods attach to the consignment they belong to, so a unit cost reflects what that specific consignment carried — which is the mechanism that lets pre-change and post-change stock hold different, correct costs.
A rate you control, with dates recordable
The rate is yours to set and change, and a rate can be given a start and an end date.
No tax on the purchase side, anywhere
A purchase order in our product has nowhere to record tax. On a cascading instrument that matters less, because the tax belongs in the cost anyway; the day it becomes recoverable, it matters a great deal. Commissionable, with a written specification, a timeline and a price.
Scheduled rate changes do not actually fire
A rate can be given dates and nothing acts on them — there is no switch on the date and no prompt. So the change is a thing somebody must do, on the morning, deliberately. We would rather write that down than let you assume a date in a field is a plan.
One rate per organization per tax type
Where a sector rate sits above the standard one, a single default cannot express both. Also commissionable, and also not built today.
Any opinion about restatement
Whether and how a balance should be restated when the instrument changes is your adviser's judgement. We hold the detail; we do not hold a view.
The one worth acting on before anything else
A field that holds a date but does not fire on it is the most dangerous item in that list, because it looks like automation. If your plan for the cutover is "the system will switch", the plan is a person — and it is much better to know that in advance and put the date in a diary than to find out from a document raised at the wrong rate.
The general question
Whenever a jurisdiction changes something about a tax, the useful question is not "what is the new rate" but "is this the same kind of tax as before?" If yes, the work is arithmetic and dates. If no, then the money changes category — cost becomes receivable, or receivable becomes cost — and everything downstream of unit cost is affected: valuation, margin, pricing, and the comparability of this year to last.
Liberia is the clean case because both instruments are named in law. Most are not that obliging, which is why the question is worth asking out loud.
What is built here, what is not, and what we would decline is on the Liberia market page. The costing mechanism this post depends on is the invoices that arrive three weeks after the goods, and the version of this argument for a market that has only ever had a non-creditable tax is the tax you paid is part of what the goods cost.
