A charge needs an amended cap
An approved USD 5,000 cap with USD 4,000 already billed has USD 1,000 headroom. A USD 1,500 proposed charge takes the billed subtotal to USD 5,500, leaving USD 500 above the cap.
Project billing
Free Project Billing Cap Calculator
Check whether the next charge fits within a client's purchasing cap. Use amounts on the same tax basis and for the same cap period, then resolve an excess before sending an invoice that the client cannot approve.
What you can do here
Compare already-billed and proposed charges with an approved project or PO cap, showing remaining headroom and any excess.
Built for real invoice workflows
Once the cap and scope approval are resolved, preview the invoice and schedule delivery.
Preparing your calculator with today’s date…
Calculation notes
How the result is calculated
Headroom before the charge = max(0, cap − already billed). Projected billed subtotal = already billed + proposed charge. Excess = max(0, projected subtotal − cap). Headroom after the charge is never negative. This is a purchasing check, not a project cost or profit calculation. Payments do not restore cap headroom.
Formulas and examples reviewed October 2, 2026. Illustrative figures; no tax or contractual determination.
Payment does not reopen the budget
A USD 10,000 cap with USD 8,000 already billed leaves USD 2,000 headroom even if all USD 8,000 has been paid. A proposed USD 1,200 charge leaves USD 800 headroom after billing.
Questions about this calculation
Should the cap include tax?
Use the basis specified by the approval or PO and enter all three values consistently. Do not compare a tax-inclusive invoice with a before-tax cap without reconciling the basis.
Does headroom mean extra work is approved?
No. A budget can have headroom while the proposed work is outside the agreed scope. Confirm both scope and spending authority.
How to use it
1
Enter the approved cap and its relevant billed subtotal.
2
Add the proposed charge on the same currency and tax basis.
3
Review any amount above the cap with the authorized approver before billing.
Why it helps
Keep paid invoices counted against the purchasing cap.
Make the approval shortfall visible before submission.
Separate budget headroom from authority to bill specific work.
Next step
From free tool to live invoice workflow.
Use the result when creating your invoice in InvoiceAgent. Planner setup links carry the settings they describe into a draft. Review your dates, amounts, PDF, and reminder settings before scheduling.
Related workflows
Move from the quick answer into the rest of the invoice system.
Check PO requirements
Check PO requirements
Match the charge to the client's actual purchasing process.
Request scope approval
Request scope approval
Document the price and schedule impact of extra work.
Invoice templates
Invoice templates
Use the result inside invoice formats that are ready for clients and easier to automate.
Knowledge base
Knowledge base
Review the billing concepts behind the numbers before they go onto a live invoice.
Profession pages
Profession pages
See how freelancers, consultants, and agencies apply the same calculator output in different workflows.