Input tax credit, and why your vendor's filing is your problem

Under GST, tax is charged at each stage of a supply chain, and a registered business can generally offset the tax it paid on its purchases against the tax it collects on its sales. The offset is input tax credit.

The intent is that tax falls on value added rather than accumulating at every handover. The mechanism is straightforward. The conditions attached to it are where construction organisations lose money, and they lose it for reasons that have very little to do with tax and everything to do with record keeping.

As with anything of this kind: the rates, the categories and the boundaries are your accountant's territory. What follows is the shape of the mechanism and the operational habits it demands.

The conditions, in outline#

Credit is not automatic on having paid tax. Broadly, a set of conditions has to be satisfied: you must hold a valid tax invoice or equivalent document, the goods or services must actually have been received, the tax must have been paid to the government by the supplier, and you must have accounted for it in your own return within the applicable time limits.

Two of those four are outside your control, and one is entirely in somebody else's hands.

The condition that makes it operational#

The supplier must have declared and paid.

This is the one that changes how a purchase department has to behave. Your credit depends on a third party filing their return correctly, on time, with your registration correctly stated on the right invoice.

If they do not, your credit is at risk regardless of the fact that you paid them the tax in good faith. The recovery route is commercial — you chase the supplier — and the commercial leverage you have is whatever money of theirs you are still holding.

Which produces the single most useful operational rule in this area: the tax component of an invoice is not the same kind of money as the rest of it, and it is worth knowing whether the supplier has filed before the last payment goes out. Once you have paid in full, the leverage is gone and you are relying on goodwill.

Reconciliation is a monthly discipline, not an annual one#

Your books say you have a certain amount of credit. The tax system says your suppliers have declared a certain amount against your registration. These two figures will differ.

Every difference falls into one of a small number of categories:

• Timing. They filed in a later period than you booked. Resolves itself.
• Your error. Wrong registration captured, invoice booked twice, credit claimed on something ineligible.
• Their error. Your registration typed wrongly, invoice reported against another customer, invoice not reported at all.
• Their failure. They have not filed.

Only the last two require chasing, and you cannot tell them apart from a total. This is exactly the argument for reconciling monthly rather than at year end: a small difference over one period is traceable to specific invoices, and a large one over a year is a project. Classifying every difference by cause is also what settles a plain balance confirmation — when your ledger and theirs disagree.

It is the same argument, structurally, as the one for counting stock small and often. A residual computed over a long period absorbs every kind of error and identifies none of them.

The restriction construction has to know about#

There are categories of expenditure on which credit is blocked, and one of them matters enormously in this industry: credit relating to the construction of immovable property is restricted in defined circumstances.

The precise boundary — what counts as construction, what counts as plant and machinery, what happens when the property is built for sale rather than for own use, what happens with works contract services — is genuinely complicated, has been litigated, and is not something to determine from a blog post.

What every purchase and accounts person in construction should know is simply that the restriction exists and is expensive, and that assuming credit is available on everything is the single most costly wrong assumption in the area. Get the position for your own circumstances from your accountant, in writing, and then encode it in how purchases are categorised at entry rather than discovering it at filing time.

What this demands of the purchase process#

The tax conditions convert several things that look like clerical details into material controls.

Vendor registration details, validated at creation. Not at first payment. An invoice from a vendor whose registration was never verified is a credit you may not be able to claim, and it is far easier to fix before any money has moved.

Correct particulars on the invoice. Registration numbers, invoice number and date, place of supply, description, rate and amount of tax. An invoice with defective particulars can usually be replaced while it is unpaid. Afterwards it becomes a favour you are asking.

The receipt of goods, recorded. One of the conditions is that the goods or services were actually received. A purchase ledger that cannot demonstrate receipt independently of the vendor's own paperwork is weaker on this than it looks, which is one more argument for goods receipt notes written by your own side.

Time limits observed. Credit has to be claimed within a period. An invoice that surfaces late — found in a drawer, or held back during a dispute — can become a credit you are no longer entitled to. A dispute that drags is therefore not cost-free even if you eventually win it.

Where the checking belongs#

The comparison between your ledger and what suppliers have reported is arithmetic across two datasets and belongs to a machine.

The decisions that come out of it do not. Whether to hold a payment because a supplier has not filed, whether a difference is worth pursuing, whether a relationship is worth the friction — those need somebody who knows the vendor.

The right arrangement is the one we hold to throughout our own systems: the machine produces a list of specific, evidenced differences and proposes what each one probably is; a person decides what to do about it. Not because machines are unreliable, but because a machine that acts on its own leaves behind a record that looks like a human decision and was not. The reasoning is in the machine proposes, a person decides.

The short version#

Input tax credit offsets tax paid on purchases against tax collected on sales, subject to conditions — and one of those conditions is that somebody else filed their return properly.

That makes vendor data quality, invoice particulars and monthly reconciliation into finance controls rather than clerical work.

And in construction there is a restriction on credit relating to immovable property that is large enough to change project economics. Find out where the line falls for your own circumstances before you assume which side of it you are on.