The core principle is separating who enters bills, who approves them, and who sends payment. In larger companies, these are three different people or departments. In a small business, you might not have that luxury, but you can still build controls that reduce the risk of errors and fraud.

Start with vendor management. Maintain a list of approved vendors. Before adding a new vendor, verify they’re legitimate by confirming contact information and validating bank account details for ACH payments. Fraudsters often impersonate existing vendors with slightly different payment details. Having a standard process for adding and changing vendor information prevents fake invoices from getting paid.

Require documentation for every bill. No invoice, no payment. This seems obvious but it breaks down quickly when busy owners approve verbal requests or handwritten notes. Every payment should trace back to an invoice, and ideally to a purchase order or contract for larger amounts. Keep these records organized so you can find them later.

Implement an approval process before payment. Even if you’re the only decision-maker, build in a deliberate review step. Set approval thresholds where anything over a certain amount requires explicit sign-off. Review invoices for accuracy, proper authorization, and reasonableness. Does this amount match what you expected? Is this vendor someone you actually use?

Separate bill entry from payment when possible. If you have even one employee handling bookkeeping, have them enter bills but reserve payment approval for yourself. If you’re doing everything alone, at least separate the timing. Enter bills one day and review and pay on another. Fresh eyes catch things you miss when rushing through.

For payment execution, limit who has access to payment methods. If using checks, keep them secured and consider requiring two signatures for amounts over a threshold. If using ACH or online banking, restrict login access and use multi-factor authentication. Review bank statements monthly to catch unauthorized transactions.

Bank reconciliation is your safety net. Reconcile every month, comparing your records to the bank statement. This catches duplicate payments, unauthorized transactions, and errors. If someone other than the person paying bills can do the reconciliation, even better. Bookkeeping cleanup and catch-up services often uncover payment issues that went unnoticed because reconciliation fell behind.

Review vendor statements periodically. Vendors track what you owe them independently. Comparing their statements to your records catches missing invoices, duplicate payments, and disputes before they become problems.

Using software with built-in workflows helps. QuickBooks and similar platforms track bill entry dates, approval status, and payment history. This creates an audit trail showing who did what and when. A bill payment service can automate approvals and maintain documentation in one place.

The goal isn’t perfect security. The goal is making errors obvious and fraud difficult enough that you catch problems before they become serious. Even basic controls implemented consistently are far better than none at all.