Invoices are more than just payment requests—they’re communication tools between your finance team and your clients. A well-structured invoice helps clients understand what they’re paying for, why, and when. For finance leads in SaaS businesses, customizing invoice fields isn’t about adding complexity. It’s about making them clear, consistent, and actionable.
In this article, we’ll look at 10 practical custom invoice fields that help you personalize invoices and reduce confusion for clients, while giving your internal teams better visibility into financial activity.
Why Custom Fields Matter
In fast-scaling SaaS businesses, standard invoice templates often fall short. Different customers have different billing requirements—purchase orders, tax details, project references, or subscription terms. Custom invoice fields let you meet those needs without rebuilding your process for every account.
They also reduce back-and-forth communication between teams. Instead of handling invoice corrections or clarifications manually, you can automate the inclusion of all the information your customers expect to see. That means fewer disputes, faster payments, and cleaner financial records.
1. Purchase Order (PO) Number
Many enterprise customers require a PO number to process payments internally. Adding this field ensures invoices pass through their procurement workflow without delay.
Why it matters: It prevents payment bottlenecks and supports compliance for clients using purchase order systems.
2. Subscription or Plan ID
For SaaS companies offering multiple subscription tiers, identifying which plan an invoice corresponds to helps with internal tracking and forecasting.
Why it matters: It connects invoicing to recurring revenue reporting, making it easier to audit billing by product line or plan type.
3. Billing Contact Name and Email
A simple field that’s often overlooked. Including the specific billing contact ensures invoices don’t get lost in a general inbox or ignored by non-finance staff.
Why it matters: It improves communication and accountability on both sides, helping your team follow up efficiently.
4. Project or Campaign Reference
This is especially valuable for SaaS businesses that bill customers for add-ons, implementation projects, or marketing-related services.
Why it matters: It links revenue to specific initiatives, helping both you and the client track ROI and allocate budgets accurately.
5. Tax Identification or VAT Number
Global SaaS companies must meet local tax compliance standards. Including tax identification details helps you avoid delays and legal complications in cross-border billing.
Why it matters: It supports compliance and simplifies record-keeping during audits or filings.
6. Payment Method or Gateway Reference
Listing the payment method or gateway used for a transaction adds transparency. It can also help your support or finance team troubleshoot failed payments.
Why it matters: It gives internal clarity on payment flows and reduces time spent tracking transactions across multiple processors.
7. Account Manager or Customer Success Rep
Including the name and contact info of the account manager or success rep personalizes the invoice experience. Clients know exactly who to contact for questions.
Why it matters: It reinforces relationship-based billing and helps maintain trust in long-term client relationships.
8. Contract Start and End Dates
For SaaS contracts with multi-term agreements, listing the service period covered by each invoice prevents confusion about renewals or upcoming billing cycles.
Why it matters: It improves forecasting accuracy and reduces renewal disputes.
9. Notes or Custom Message Section
This section lets you add important details like discounts, billing reminders, or a simple thank-you message. Small touches like this create a better client experience.
Why it matters: It adds clarity and builds rapport without requiring a separate email or ticket.
10. Payment Terms and Late Fee Policy
While most invoices list due dates, few include detailed payment terms. Adding specifics—like “Net 30” or “1.5% late fee after 30 days”—sets clear expectations.
Why it matters: It minimizes late payments and provides written documentation for your finance policies.
Automating Custom Fields With Billing Software
Manually adding these custom fields can quickly become unmanageable as your customer base grows. That’s where automation helps. Using a subscription billing platform that supports customized invoicing options allows you to include the right fields automatically, based on customer type or billing frequency.
For example, with ChargeOver’s custom billing automation, finance teams can create rule-based invoice templates that populate PO numbers, payment terms, and tax details automatically—ensuring accuracy at scale.
If you manage clients across multiple regions or payment methods, integrating flexible payment solutions can further streamline how invoices are generated and paid, without requiring manual intervention.
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