Custom invoicing software vs Exact and Moneybird

What to look at first

Do not rebuild accounting unless needed. Often the right solution is a custom invoicing layer connected to bookkeeping.

• Map pricing and approval rules.
• Keep bookkeeping as source of truth.
• Automate invoice creation.
• Sync status and payments.

What the result should be

The company gets flexible invoicing without breaking financial control.

Make the decision from the operating process

Keep the accounting product as financial source and customise the operational billing layer when pricing, milestones, subscriptions or approval rules are specific.

• Document tax, price and correction rules.
• Use stable references to prevent duplicate invoices.

A realistic operating example

Approved project work becomes a draft invoice, is checked and then sent to accounting by API. Invoice number and payment status synchronise back.

A controlled implementation sequence

Deliver the smallest complete workflow first. Test exceptions with the people who perform the work before adding more features.

• Create traceable draft lines.
• Validate customer, tax and total.
• Send idempotently and log responses.

Measure adoption and operating value

Set a baseline before launch and review both business results and manual recovery.

• Time from delivery to invoice.
• Corrections, duplicates and rejected transactions.

Important limits and safeguards

AI may extract or flag information, but final financial rules must remain deterministic and auditable.

Separate operational billing from financial accounting

Accounting software should usually remain authoritative for invoice numbers, tax, receivables and ledgers. Bespoke work belongs in the layer before it: specific pricing, subscriptions, project milestones, usage, approvals or multiple entities. Define when delivery becomes billable and which evidence finance needs. This automates the distinctive operation without rebuilding a complete accounting product and its controls.

• Operations owns delivered work and pricing input.
• Billing creates traceable draft lines.
• Accounting validates customer, tax and numbering.
• Payment and correction status returns to operations.
• One stable reference connects every system.

Model pricing, periods and corrections explicitly

Every line should trace back to a contract, order, timesheet, volume or milestone. Preserve the rate version and period so later changes do not rewrite history. Define rounding, minimum commitment, discount, indexation, currency and tax. Correct through credit and rebilling rather than editing a sent invoice. A tested rule engine is more dependable than asking generative AI to decide an amount.

• Pricing source, effective date and contract reference.
• Calculation and rounding by line.
• Approval for exceptions, discounts and high values.
• Credit and rebilling with audit history.
• Test cases for boundary dates and exceptions.

Build an idempotent accounting integration

A retry after network failure must never create a second invoice. Give each billable set a stable key and store draft, approved, sent, accepted or rejected state. Post server-side through the official API, log request and response without unnecessary personal data, and route errors to a visible queue. Reconcile that every approved draft has exactly one financial invoice and matching totals.

• Unique external reference per billing event.
• Explicit states and permitted transitions.
• Retry using the same idempotency key.
• Owned error queue with recovery action.
• Daily reconciliation of count, amount and currency.

Keep portal, payment and reminders on one status

A customer must not see a different invoice state from finance. Display the financial document and current status from the source. Use a specialist payment provider or accounting integration and accept changes only from verified callbacks. Reminder logic should respect disputes, credits and customer policy, preventing automated messages while a case is under review.

• Role-protected document access.
• Payment link tied to invoice and amount.
• Verified webhook and duplicate-payment protection.
• Reminder pause during dispute or correction.
• One timeline for support and finance.

Pilot one billing stream and measure end to end

Choose a representative invoice type with meaningful volume and limited exceptions. Run drafts beside the current process and compare customer, tax, lines and total. Finance should accept the flow before automatic sending is considered. Measure delivery-to-invoice time, correction, rejected transactions, ageing drafts and rekeying. Expand later to subscriptions, entities and complex contracts.

• Baseline cycle time and recovery work.
• Test set of normal and exceptional invoices.
• Four-eyes control during initial production.
• Fallback during API or accounting outage.
• Stop-or-go based on accuracy and released capacity.