A department needs $18,000 worth of new equipment.
Why not simply order it, wait for the invoice, and record the expense?
For a very small purchase, that may feel perfectly reasonable.
But as purchasing volume increases, businesses usually need to answer three different questions:
Did someone approve the purchase?
What exactly did we agree to buy?
Does the invoice match what was actually authorized?
Those questions happen at different points in the purchasing cycle.
That’s why a purchase requisition, purchase order, and vendor invoice are not three names for the same document.
They represent three different stages of financial control.
Stage 1: The Purchase Requisition
A purchase requisition begins inside the company.
Imagine an operations manager needs 12 new laptops.
The manager hasn’t necessarily purchased anything yet.
Instead, they submit a request.
The requisition might identify:
- What is needed
- Quantity
- Expected cost
- Department
- Business purpose
- Requested vendor
- Required date
At this point, the important question is:
Should the company make this purchase?
The requisition gives the organization an opportunity to answer that question before money is committed.
Approval Before Commitment Matters
Suppose the laptops cost $18,000.
The operations manager may have authority to request them but not authority to independently commit $18,000 of company funds.
An approval workflow can route the request according to the company’s rules.
Perhaps purchases under $2,500 need department approval.
Larger purchases require another level.
Capital purchases may follow a different path entirely.
The specific rules depend on the organization.
The principle is what matters:
authorization happens before the commitment whenever the process requires it.
Without that step, finance may first learn about the purchase when an invoice arrives.
By then, the conversation has changed from:
“Should we buy this?”
to:
“We already bought this. Can someone approve the bill?”
Those are very different controls.
Stage 2: The Purchase Order
Once the purchase is approved, the company can create a purchase order.
The PO represents what the company intends to purchase under the agreed terms.
For example:
Vendor: Technology Supply Co.
Item: Laptop computers
Quantity: 12
Price: $1,500 each
Total: $18,000
Now the company has a reference point.
The purchase order answers:
What did we authorize and order?
This becomes important later because memories are unreliable.
Someone may remember that the quote was “around $18,000.”
The PO records the actual authorized details.
A PO Creates Visibility Before the Invoice Exists
This is an important accounting concept.
An invoice tells finance about an obligation after the vendor bills the company.
A purchase order can provide visibility into expected spending before that invoice arrives.
Imagine a department has a $100,000 equipment budget.
Only $55,000 has been recorded as actual expense so far.
At first glance, it appears to have $45,000 remaining.
But there are already approved purchase orders totaling $38,000.
The department doesn’t really have the same freedom that the $55,000 actual figure suggests.
This is why commitments matter in purchasing analysis.
Looking only at posted expenses can provide an incomplete picture of what the business has already agreed to buy.
Stage 3: The Vendor Invoice
The equipment arrives.
Then the vendor sends an invoice for $18,000.
Now the third question appears:
Does the bill correspond to what we ordered?
The invoice is the vendor’s request for payment.
It isn’t the original internal request.
It isn’t the company’s purchasing authorization.
It is a separate financial document representing the amount the vendor says is owed.
That distinction is what makes comparison possible.
What Happens When the Invoice Doesn’t Match?
Suppose the invoice arrives for $19,800 instead of $18,000.
Now finance has something concrete to investigate.
The PO says:
12 laptops × $1,500 = $18,000.
The invoice says:
$19,800.
Why?
Maybe shipping was added.
Maybe the unit price changed.
Maybe an additional item was included.
Maybe the vendor made an error.
Maybe someone changed the order without updating the purchasing documentation.
The mismatch itself isn’t proof that anything is wrong.
It’s a signal that the difference needs an explanation.
Quantity Differences Matter Too
Price isn’t the only thing that can change.
Suppose the company ordered 12 laptops.
The invoice bills for 12.
But only 10 were received.
If the purchasing process includes receiving information, the company has another comparison point:
What was ordered?
What was received?
What was invoiced?
Those three numbers aren’t guaranteed to match.
And when they don’t, the difference matters.
This Is the Logic Behind Matching
A purchasing workflow becomes much stronger when documents can be compared rather than reviewed in isolation.
A common concept is matching information across the purchasing cycle.
The organization can compare the purchase order with the invoice and, where applicable, receiving information.
The purpose isn’t bureaucracy for its own sake.
It’s answering a very practical question:
Are we being billed for what the company actually authorized and received?
Sage Intacct Connects These Purchasing Stages
Sage Intacct Purchasing supports purchasing workflows that can move activity through stages such as requisitions and purchase orders while connecting purchasing activity with the broader financial system.
That connection matters.
The purchasing process shouldn’t exist in one universe while accounting discovers the financial consequences later.
The earlier finance can see authorized commitments and purchasing activity, the better the organization can understand upcoming obligations.
Departments and Finance See Different Parts of the Same Purchase
The requesting department cares about the operational need.
“We need these laptops before the new team starts.”
Procurement may care about vendor terms and purchasing rules.
Finance cares about authorization, budget impact, accounting treatment, and the eventual liability.
Accounts payable cares about whether the invoice is ready to be processed.
These aren’t competing perspectives.
They’re different responsibilities surrounding the same transaction.
A structured purchasing workflow gives each stage a clear purpose.
Why Invoice-Only Purchasing Can Become Dangerous
Imagine a company where the standard process is:
- Someone buys something.
- Vendor sends invoice.
- Finance asks who ordered it.
- Someone searches through email.
- A manager confirms the purchase.
- Finance records the bill.
The company technically has an approval process.
But approval is happening after the economic decision has already been made.
That reduces its value as a spending control.
A requisition-and-PO process moves important decisions earlier.
Not Every Purchase Needs the Same Workflow
Structure shouldn’t mean treating a $30 office supply order exactly like a $300,000 equipment purchase.
Businesses can establish purchasing rules appropriate to their operations.
Different transaction sizes or categories may require different approval levels.
The useful principle is proportional control.
More significant commitments generally deserve more visibility before they become obligations.
The Three Documents Answer Three Different Questions
The distinction becomes simple when each document is attached to its purpose.
Purchase Requisition
Can I buy this?
An internal request for authorization.
Purchase Order
What have we agreed to buy?
A documented purchasing commitment.
Vendor Invoice
What is the vendor asking us to pay?
The bill presented by the supplier.
When those stages are connected, the organization gains a history of the decision rather than seeing only the final bill.
The Real Value Is What Happens Before Payment
It’s easy to think of purchasing as an accounts payable problem.
But by the time an invoice reaches accounts payable, several important business decisions may already have happened.
Someone identified a need.
Someone selected what to buy.
Someone chose a vendor.
Someone agreed to a price.
Someone committed company resources.
Sage Intacct’s purchasing workflow helps bring structure to those earlier stages instead of beginning financial control only after the invoice arrives.
Because the best time to discover that an $18,000 purchase wasn’t authorized isn’t when someone is asking why the vendor hasn’t been paid.
It’s before the order is placed.