MosoFin skill · ar-aging-and-collections · learning guide

From one late invoice to the customers you chase first

This page shows how the skill builds an A/R aging and a collection plan, one level at a time. It starts with one invoice in one bucket. It ends with the customers that the skill must not chase. The page quotes every rule from the skill and works every number in front of you.

The rules are the skill's ownThe page quotes each rule word for word, with the file and section it comes from.

Outside sources back the factsThey are two sections of an OpenStax textbook, an IRS page, a Federal Reserve survey and a US courts glossary. Each one has a number and a link.

The page shows the mathOpen "Check it yourself" on any level. Follow every line on a calculator.

Your numbers, your checkAt the end, enter up to 10 invoices of your own. The page builds the aging, the metrics and the plan, and it calculates DSO.

Rule: quoted from the skill Fact: from a cited authority, numbered like ¹ Example: made-up figures, calculated in full

How it thinks

Twelve rules the whole skill runs on

Every level below applies one or more of these rules. The examples use one made-up company, Northbrook Trading, which keeps its books in US dollars on the accrual basis. The as-of date is Wednesday 30 September 2026. Five customers owe Northbrook money, and a sixth customer has a credit.

Learning path

Six levels, from simple to complex

Check it yourself

Put in your own customers

Enter up to 10 open invoices or credits, or load the example. Part 1 runs Steps 2, 3 and 5 from references/method.md. Part 2 calculates DSO. The page sends nothing anywhere.

Part 1: Age your own invoices

The aging As-of date A/R balance on the balance sheet (optional)

How the page ranks

Enter a credit as a negative amount with no due date. The page ranks late customers by the age of the oldest invoice, then by open balance. It routes a customer with an insolvency notice to professional review. It routes a disputed invoice to the dispute owner. A customer with a net credit goes to Exceptions.

Customer	Invoice	Due date	Open amount	Disputed	Insolvency notice

The page counts days past due in whole calendar days: the as-of date minus the due date. Zero or less is Current. Metrics use the net open balance, and the weighted days use the gross invoices with Current counted as 0 days. The page asks for no due date on a credit. On an invoice with no due date, it gives no bucket and leaves the invoice out of the totals. This example ranks by age first and then by open balance. The skill does not say which comes first, so that order is this page's choice. The preset gives a net A/R of $68,200 and a difference of $750 to the books. A plan from the calculator is a proposal. A person reviews it and decides who to contact.

Part 2: DSO

The period Ending A/R, net Days in the period

The sales base Credit sales: invoices less credit memos Total income (optional, for the proxy)

The page uses the skill's formula: ending A/R ÷ credit sales × days in the period. The OpenStax textbook uses average A/R and 365 days, so its figure can differ. The preset gives 43.0 days on credit sales and 33.0 days on total income. The skill shows the proxy only with your approval, and always with its label.

Using it

What it asks, needs and gives back

Asks firstUse MosoFin for this run, or upload the data yourself? As of which date? Do you need the aging only, a collection plan, DSO or drafts, for all customers or one? For DSO, which period, and on the upload path, what are your credit sales? Any disputes, credit holds, tiers or payment history? What is your collection policy? It also tells you that an aging is always on the accrual basis.

NeedsThe skill needs the A/R aging detail as of the date, with one row for each open invoice. The aging summary and the A/R balance on the balance sheet make the tie-out stronger. You type in the company name, the as-of date and the base currency.

Gives backThe skill gives back seven sheets: run context, aging summary, aging detail, collection plan, drafts, exceptions and coverage. It asks before it makes an Excel file.

NeverThe skill never reads your data before you answer its questions and say yes to its read-back. It never writes to your books, contacts a customer or forces a tie. It never guesses disputes or holds from the ledger, and never shows a proxy DSO without its label.

Sources

Where every fact on this page comes from

The rules are the skill's own. The facts below come from five outside sources. They are two sections of an OpenStax textbook, an IRS page, a Federal Reserve survey and a US courts glossary. MosoFin checked each one on 28 October 2026 from search results and did not open the pages. Follow the link for today's wording.

Not backed by an outside authority. The six buckets, the action bands, the 0.01 tolerance, the seven sheets and the draft mark are the skill's own. MosoFin made up Northbrook Trading, its customers and every figure in the examples. The page marks them where they appear.