Accounts receivable

Accounts receivable (AR) is the money customers owe a business for goods or services it has already delivered and invoiced but has not yet been paid for. It sits on the balance sheet as a current asset and turns into cash when the invoice is paid.

What is the difference between accounts receivable and accounts payable?

Accounts receivable is money coming in and accounts payable is money going out. Both come from the same invoices, seen from opposite sides: an unpaid invoice you sent is a receivable for you and a payable for your customer. Collecting a receivable is active work, because the cash arrives only when someone at the customer approves and releases the payment.

Accounts receivable compared with accounts payable on direction of cash, balance sheet side and who has to act.
	Accounts receivable	Accounts payable
Direction of cash	Money customers owe you	Money you owe suppliers
Balance sheet	Current asset	Current liability
Who has to act	You, by following up until the customer pays	You, by paying on time and keeping your own terms

How do you read an accounts receivable aging report?

An aging report groups every open invoice by how long it has been past due, so you can see which customers to contact first. The buckets below are a common layout. The actions put the call first and the written follow-up second.

Accounts receivable aging buckets with what each one usually means and the first action to take.
Bucket	What it usually means	First action
Current	Not yet due	Check the invoice was delivered and reached the right person
1 to 30 days past due	An oversight or an approval that is stuck	Call, then send the invoice link on WhatsApp
31 to 60 days past due	A real blocker, or a low priority at the customer	Second call to the person who approves payment, then a written notice by email
61 to 90 days past due	The invoice is at risk	Call the account owner, offer a payment plan and pause new credit
Over 90 days past due	Unlikely to be paid without escalation	Decide: payment plan, collections agency or write-off

How do you calculate days sales outstanding?

Days sales outstanding (DSO) is the average number of days it takes to collect payment after a sale. The formula is (accounts receivable ÷ total credit sales) × the number of days in the period. A company with $500,000 in receivables and $3,000,000 in credit sales over a 90-day quarter has a DSO of about 15 days. Compare it with your payment terms: if you sell on net 30 and your DSO is 45, customers are paying about two weeks late on average. A falling DSO is the clearest sign that your follow-up is working.

What should you do when an invoice goes overdue?

Pick up the phone first. A call is the only channel where you learn why the invoice is unpaid and agree a payment date on the spot. The other channels support the call.

Phone, WhatsApp, SMS and email compared for chasing an overdue receivable on strength and weak spot.
Channel	Best for	Weak spot
Phone call	Finding the reason and agreeing a payment date	Needs someone to dial at scale, or an AI voice agent
WhatsApp	Sending the invoice and payment details right after the call, and getting a reply	Needs a mobile number and the customer's consent
SMS	A short nudge to any mobile number	No attachments and no thread
Email	A written record with the invoice attached	Easy to ignore

A first overdue call can follow four lines:

Say who you are and which invoice you are calling about, with the number and amount.
Ask whether the invoice arrived and whether anything is blocking payment.
Ask for a specific payment date and repeat it back.
Say you will send the invoice link on WhatsApp now, and note the date for follow-up.

If the customer disputes the invoice, stop the reminders for that invoice and pass it to whoever owns the dispute.

Do debt collection laws apply to business invoices?

In the US, the federal Fair Debt Collection Practices Act covers consumer debt only. It defines a debt as an obligation from a transaction made mainly for personal, family or household purposes (15 U.S.C. § 1692a(5)). Ordinary business-to-business invoices usually fall outside it, so your payment terms, the contract and state law set the rules. Check them before you add late fees, and ask a lawyer about anything beyond routine reminders.

How does AI fit into accounts receivable follow-up?

The call step is the one most teams skip, because it takes hours of dialing. An AI voice agent can work through your aging report from the oldest bucket forward. It records the promised payment date, sends the WhatsApp message with the invoice link and flags the invoices that need a person. That is what Sono's payment reminder calls do. For the staged sequence, read dunning and the guide to the dunning process, or see how automation fits the wider accounts receivable workflow.