Interim Invoice Template
An interim invoice bills for the part of a long engagement that has happened so far, while the work carries on. It is a real invoice: it asks for payment now, carries its own number and due date, and counts as a sale in your records. What makes it interim is the context it has to carry. The client needs to see which period or stage this bill covers, how it was worked out (hours times rates, a share of a fixed fee, or an agreed instalment), what has already been billed and paid, and how much of the budget or contract is left. That running picture is what lets a client approve the third or fourth bill on the same matter without asking for a reconciliation. This template is built around it: a billing period, an interim number within the engagement, cumulative totals and a remaining-budget line. The download is an editable HTML invoice with invoice number, dates, a line-item table and totals. Fill it in your browser and print it or save it as PDF.
Preview this editable document
Download the HTML file to edit its fields, then print or save as PDF. Totals are entered manually.
What This Template Includes
- Engagement, contract or matter reference
- Interim number within the engagement (for example Interim 3)
- Billing period covered (from and to dates)
- Billing basis: time and materials, share of fixed fee, or agreed instalment
- Work this period: task or role, hours and rate
- Expenses this period, at cost, with receipt references
- Previous interim invoices: numbers and amounts
- Billed to date, including this invoice
- Payments received to date
- Estimate, budget or contract value, and the amount remaining
- Retention withheld, only if the contract provides for it
- Statement that a final invoice will follow
How to Create Your Interim Invoice
- 01
Describe your work
Type a plain English description of the services you provided, the client, and the amount.
- 02
AI generates your invoice
InvoiceQuickly's AI drafts the client, line items, dates, and totals for you to review before saving.
- 03
Review, download, and send
Check every detail, download the PDF, or use Pro to email the PDF directly to your client.
Recommended Payment Terms
Agree the rhythm before the work starts and put it in the engagement letter or contract: monthly in arrears is the most common for time-and-materials work, while fixed-fee work is usually split into equal instalments or a share of the fee per period. Keep the cut-off consistent (for example the last day of each month) and send each interim invoice within a few days of it, because every day of delay is a day added to the client's payment cycle. Net 30 suits most business clients; net 14 or 15 suits smaller engagements. State in the contract what happens if an interim invoice is not paid, such as pausing work after a stated number of days, and repeat that term on each invoice. If the client works to a budget or purchase order, ask how they want to be told when billed-to-date reaches a threshold such as 75%, so the budget is extended before the work runs out of cover rather than after.
Need help writing payment terms? Read our guide to invoice payment terms for best practices and templates.
Tax Information
Each interim invoice is taxed like any other invoice for the work it covers. United States: whether sales tax applies depends on your state and the service; many professional services are not taxed, but some states tax specific services, so check your state's revenue department for the service you provide. United Kingdom: ongoing services billed periodically are treated by HMRC as continuous supplies, where 'the tax points are restricted to the issue of a VAT invoice or the receipt of a payment, whichever is the earlier' (HMRC VAT Time of Supply manual, VATTOS9155). So issuing a VAT invoice for an interim bill makes the VAT due for that period even if the client has not paid. Some suppliers instead send a request for payment clearly marked 'This is not a VAT invoice' and issue the VAT invoice once paid; HMRC says such a document creates no tax point provided it is not a VAT invoice (VATTOS9165). InvoiceQuickly applies one tax percentage per invoice and copies your saved business tax ID to new invoice PDFs; check the saved IDs and PDF before sending when it must appear. General information, not tax advice.
Industry context (2026)
Interim billing is written into many standard contracts. On US federal time-and-materials and labor-hour contracts, FAR clause 52.232-7 (November 2021) says vouchers 'may be submitted not more than once every two weeks' and lets the contracting officer withhold 5 percent of the amounts due, with the total withheld capped at $50,000 per contract (acquisition.gov, accessed 28 October 2026). Private engagement letters usually set their own rhythm, most often monthly. In the United Kingdom, HMRC treats services supplied and billed periodically as continuous supplies: the tax points are the issue of a VAT invoice or the receipt of a payment, whichever is earlier, and a request for payment that is not a VAT invoice creates no tax point (HMRC VAT Time of Supply manual, VATTOS9155 and VATTOS9165, updated 8 April 2025, accessed 28 October 2026). Construction projects usually call the same idea progress billing, with a schedule of values and retainage. General information, not legal or tax advice.
Worked example
Worked example (illustrative rates, not market data): a US operations consultancy runs a six-month process-improvement engagement for Harbor Logistics on time and materials, with a fee estimate of $58,000, expenses at cost, monthly billing in arrears and net 30 terms. Interim 1 (July) billed $9,500 in fees and $360.00 in expenses; Interim 2 (August) billed $12,000 in fees and $415.50 in expenses. Both are paid: $22,275.50. On 2 October the consultancy issues INV-0142, Interim 3, for 1 to 30 September 2026, due 1 November. Line 1: senior consultant, process mapping and workshops, 46 hours × $150.00 = $6,900.00. Line 2: analyst, data collection and modelling, 72 hours × $95.00 = $6,840.00. Line 3: travel to the client's Savannah site, 17 to 18 September, at cost, receipts attached, 1 × $612.40. Subtotal $14,352.40, tax 0% (set it from your state's rules), total due $14,352.40. Notes: 'Interim 3 of the Harbor Logistics engagement. Fees this period $13,740.00; fees to date $35,240.00 of a $58,000.00 estimate (60.8%), remaining $22,760.00. Expenses to date $1,387.90. Billed to date including this invoice $36,627.90; paid to date $22,275.50. A final invoice will follow at completion.' Check: $9,860.00 + $12,415.50 + $14,352.40 = $36,627.90, and $35,240.00 + $1,387.90 = $36,627.90. The client can see at a glance that 60.8% of the fee estimate is used after three of six months, which is the conversation to have now, not in month six.
Common mistakes to avoid
No billing period
'Consulting services: $14,352.40' with no dates forces the client to guess which hours are included. Put the from and to dates of the period on every interim invoice.
Losing the running total
Each interim bill on its own looks fine, but the client approves against a budget. Show billed to date, paid to date and the remaining estimate, or expect a reconciliation request before payment.
Billing ahead of the work
An interim invoice covers work done in the period, or an instalment the contract allows in advance. Billing future work without that agreement is a common cause of disputes and, in some regulated trades, is not allowed.
Issuing a UK VAT invoice before you are ready to pay the VAT
For continuous services the VAT invoice itself creates the tax point. If cash flow matters, send a request for payment marked as not a VAT invoice and issue the VAT invoice when paid.
Ending with another interim bill
If the last bill is labelled interim, nobody can tell the engagement is closed. Issue a final invoice that lists every interim bill and states the closing balance.
Invoicing Tips
- 1Number interim bills within the engagement as well as in your invoice sequence: 'INV-0142, Interim 3 of the Harbor Logistics engagement' tells the client exactly where this bill sits.
- 2Bill the period, not the calendar: '1 to 30 September 2026' on the invoice lets the client match it to timesheets and their own month-end accruals.
- 3Show billed to date and payments received to date on every interim invoice. It also puts any unpaid earlier bill in front of the person approving the new one.
- 4For time-and-materials work, show the estimate and the percentage used. Flagging 'fees to date 61% of estimate' early is far easier than explaining an overrun on the last bill.
- 5Keep expenses as separate lines at cost with a receipt reference, so they do not eat into the fee budget the client is tracking.
- 6Do not label the last bill 'interim'. When the work is finished, issue a final invoice that summarises every interim bill and closes the account.
Related Resources
- Progress billing guide: percentage complete, schedules of values and retainage
- Invoicing for consultants
- Invoice payment terms explained
- All invoice templates
Frequently Asked Questions
What is an interim invoice?
An interim invoice bills for part of a long engagement while the work is still under way: one month of time and materials, a share of a fixed fee, or an agreed instalment. It is a full invoice with its own number and due date, and it shows what has been billed and paid so far. A final invoice follows when the work is complete.
What is the difference between an interim invoice and a progress invoice?
Many people use the terms interchangeably. In practice a progress invoice usually bills construction work against a schedule of values, with percentage complete per line and retainage withheld, while an interim invoice is the broader term for any periodic bill during a long engagement, including consultancy, legal and agency work billed by the hour or by instalment.
What is the difference between an interim invoice and a final invoice?
An interim invoice bills one period or stage and leaves the engagement open. A final invoice is issued once the work is complete: it lists every earlier invoice, releases any retention, deducts payments and credits, and states the balance that closes the account.
How often should I send interim invoices?
As often as your contract says. Monthly in arrears is the common choice for time-and-materials work. Some public contracts set limits: US federal time-and-materials vouchers may be submitted not more than once every two weeks under FAR 52.232-7. Whatever you choose, keep the same cut-off date each period.
Do interim invoices have to be the same amount each time?
No. Time-and-materials interim bills vary with the hours worked. Fixed-fee engagements are often billed in equal instalments, but they can also be billed by the share of work completed, as long as the contract says which method applies.
Is an interim invoice a VAT invoice in the UK?
It is if you issue it as one, and then VAT for that period is due even before the client pays, because the tax point for continuous services is the earlier of the VAT invoice or the payment. A request for payment marked as not a VAT invoice creates no tax point; you then issue the VAT invoice when paid.
What should I do if a client does not pay an interim invoice?
Follow the contract: send a reminder after the due date, show the unpaid amount on the next interim invoice, and apply any agreed late-payment term or work-pause clause. Raise it early, because an unpaid interim bill means you are financing the next period of work.
Can I create interim invoices in InvoiceQuickly?
Yes, as ordinary invoices. Duplicate the previous one, change the period and lines, and keep the running totals in the notes. InvoiceQuickly has no separate interim document type or retention field. Free covers 5 invoices in total; Pro is $9 a month for unlimited invoices, email delivery and scheduled reminders.