A balance that cannot divide evenly
USD 1,000 across three installments is USD 333.34, USD 333.33, and USD 333.33. Starting October 15, 2026, at 30-day intervals gives October 15, November 14, and December 14.
Payment planning
Free Invoice Installment Plan Calculator
A payment plan spreads an existing balance across agreed payment dates. Use this planner to draft equal installments without accidentally creating a new project price or treating a promised installment as money received.
What you can do here
Split an existing invoice balance into 2–24 equal installments with exact cent reconciliation and fixed calendar-day dates.
Built for real invoice workflows
Keep the plan with the existing invoice, and review its reminder timing separately before the next follow-up.
Preparing your calculator with today’s date…
Calculation notes
How the result is calculated
Convert the balance to cents, divide by the installment count, and give one extra cent to each of the earliest installments until the remainder is allocated. Each date is the first date plus the fixed day interval times its position. A 30-day interval is not a calendar-month recurrence. No interest, weekend changes, collection attempt, or new invoice is generated.
Formulas and examples reviewed October 2, 2026. Illustrative figures; no tax or contractual determination.
A weekly year-end plan
USD 900 across three installments is USD 300 each. Starting December 24, 2026, at seven-day intervals gives December 24, December 31, and January 7, 2027. Check holidays separately with the client.
Questions about this calculation
Is this the same as milestone billing?
No. This plan schedules payments against an existing balance. Milestone billing prices separate stages of future or accepted project work.
Will InvoiceAgent collect these installments?
No. The calculator does not receive payments or change an invoice. Save the proposed schedule, obtain the required approval, and use your payment and reminder process separately.
How to use it
1
Enter the existing balance after confirmed receipts and approved adjustments.
2
Choose 2–24 installments, the first payment date, and a fixed day interval.
3
Review the amounts and dates with the client before recording an agreed plan.
Why it helps
Make installment amounts add back to the exact balance.
See dates across month and year boundaries.
Keep a payment plan distinct from milestone invoices for future 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.
Record the installment agreement
Record the installment agreement
Keep the original invoice, dates, amounts, and receipt evidence together.
Review payment-plan controls
Review payment-plan controls
Decide who approves the plan and how follow-up should 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.