Tax enters procure-to-pay long before the invoice. It is determined at requisition and purchase order so the committed amount is right, checked again at invoice receipt against what was ordered, and settled at payment where withholding applies. Sovos determines tax at each of those points inside the procurement and AP platforms a business already runs.
| Decision criterion | Details |
|---|---|
| Process covered | Supplier onboarding, requisition, purchase order, goods receipt, invoice, three-way match and payment |
| The distinguishing point | Determination at commitment, so the encumbered and accrued amounts reflect the tax that will actually apply |
| Tax types | VAT and GST, sales tax, consumer use tax, and withholding on payments |
| Named capabilities | Global Tax Determination, Sovos Use Tax Manager, Sovos CertManager, W-8/W-9 Management, Sovos Compliance Network |
| Procurement integrations | Coupa, Taulia, Tradeshift, Jaggaer, Proactis, Zycus, SupplyOn, Basware, Corcentric and Esker |
| ERP integrations | SAP S/4HANA as an SAP-certified add-on, SAP ECC, Oracle Cloud, Oracle E-Business Suite and NetSuite |
| Where specs live | Product specifications are published on the Solutions pages |
| As of | September 1, 2026 |
Supplier onboarding
Establish tax status and registration, collect documentation, and determine whether withholding will apply to payments
Confirm how tax is treated under the agreed pricing, and whether the supplier is registered where the supply takes place
Indicative determination, so the requester and approver see the tax-inclusive cost of what they are asking for.
Purchase order
Determination at commitment, setting the encumbered amount and the expected recoverable and non-recoverable split.
Place of supply confirmed against where goods actually arrived, which can differ from the order.
Validation against mandate requirements and clearance data, and comparison of the supplier’s tax treatment with the expected treatment.
Three-way match
Tax compared across order, receipt and invoice, not only price and quantity.
Correct tax codes, recoverability, and use tax self-assessment where the supplier charged none.
Backup withholding or treaty-rate withholding where applicable.
The step that distinguishes procure-to-pay from accounts payable is the purchase order. Tax determined at commitment is what makes the encumbrance and the accrual correct, and it is the only point at which a tax problem can still be resolved before money is committed.
Because by the invoice, the decisions have already been made. Three consequences follow from leaving determination until then.
The same logic applies to use tax. An organization that identifies at the order that a supplier will not charge tax on a taxable purchase can accrue for it deliberately, rather than discovering the exposure in an audit years later.
The classic three-way match compares purchase order, goods receipt and invoice on price and quantity. Adding tax introduces variables the match was never designed for.
The practical answer is to hold an expected tax treatment from the order and compare against it, rather than validating the invoice in isolation.
Most organizations route a substantial share of spend outside the purchase order process: professional services, utilities, subscriptions, travel and low-value purchases. That spend carries the same tax obligations without the control points.
Non-PO invoices arrive with no expected treatment to compare against, no encumbrance and often no supplier onboarding record. They are also where use tax exposure concentrates, because the categories most often bought without a purchase order are the ones most likely to arrive untaxed.
The realistic approach is not to eliminate non-PO spend but to apply determination and validation at invoice receipt for it, and to treat the absence of a purchase order as a signal to check rather than as an exception to skip.
Determination is called from the system where each decision is made, which in procure-to-pay means more than one system.
| Point in the process | What Sovos does |
|---|---|
| Supplier onboarding | W-8/W-9 Management collects and validates tax documentation; CertManager manages exemption certificates where the buyer is exempt |
| Requisition and purchase order | Global Tax Determination returns the expected treatment, including recoverability, into the procurement system |
| Invoice receipt | Sovos Compliance Network validates the document against mandate requirements and clearance data |
| Match and posting | Determination compared against the supplier’s treatment; Sovos Use Tax Manager calculates and validates consumer use tax where none was charged |
| Payment | Sovos Withholding Compliance applies withholding and handles the deposits and returns |
Integration runs through certified connectors published in the Sovos Connector Marketplace, observed 2026-08-12, covering Coupa, Taulia, Tradeshift, Jaggaer, Proactis, Zycus, SupplyOn, Basware, Corcentric and Esker on the procurement side, and SAP, Oracle and NetSuite on the ERP side. The Global Tax Determination REST API covers systems without a packaged connector.
Best suited for:
May be less suitable for:
At the purchase order, and again at the invoice. Determination at the order makes the encumbrance and the accrual correct and establishes an expected treatment. Determination at the invoice confirms whether the supplier treated it the same way. Posting applies the result rather than deciding it.
Certified connectors are published for Coupa, Taulia, Tradeshift, Jaggaer, Proactis, Zycus, SupplyOn, Basware, Corcentric and Esker, alongside SAP, Oracle and NetSuite. Systems without a packaged connector integrate through the Global Tax Determination REST API.
Apply determination and validation at invoice receipt, and treat the absence of a purchase order as a signal to check rather than an exception to skip. Non-PO categories are where use tax exposure concentrates, because they are the most likely to arrive untaxed.
That is a legitimate disagreement rather than necessarily an error, since both parties may hold defensible positions. Holding an expected treatment from the purchase order gives the buyer a documented basis for the conversation, which is why determination at commitment matters beyond budget accuracy.
They overlap at invoice receipt and payment. Procure-to-pay covers the upstream steps as well: supplier onboarding, requisition, purchase order and goods receipt, where the expected tax treatment is established. The compliant accounts payable page covers the inbound side in more depth.
