MosoFin skill · payroll-reconciliation · learning guide

From one payroll quarter to the exceptions you fix first

This page shows how the skill ties one quarter of payroll across four sources, one level at a time. It starts with the totals in the payroll register. It ends with the exceptions in the order of their consequence. 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 five IRS pages, an HMRC page and a section of an OpenStax textbook. 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 one payroll period of your own. The page ties the register, the books, the bank, the liabilities and the filing. It has no tax rate field.

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

How it thinks

Thirteen 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 period is the quarter from 1 July to Wednesday 30 September 2026. The owner runs the skill on Monday 19 October 2026. A payroll provider calculates the pay, and Northbrook deposits the federal taxes itself through EFTPS. Every tax amount comes from the provider's report for Northbrook. This page uses no tax rate.

Northbrook's answers to the nine intake questions

Use MosoFin, or upload the data? Northbrook uploads the data. The second example in the calculator shows the MosoFin path.
Which entity? Northbrook Trading only. It is one company with its own payroll.
Which period? The quarter that ended on 30 September 2026.
The payroll registers. The provider's register for all four runs. That includes the off-cycle bonus run, because the skill asks for off-cycle runs by name.
The bank statement. The statement for July to September.
The remittance records. EFTPS confirmations, receipts from the 401(k) provider and the state unemployment payments.
The due dates. Federal taxes by the 15th of the next month, or the next business day after a weekend or holiday. The 401(k) money by the 7th of the next month, under the plan. State unemployment each quarter, by the end of the month after the quarter. The owner gives all of these. The skill supplies none of them.
The wage base rules. The owner states them from the provider's set-up. The 401(k) pre-tax deduction makes federal income-tax wages smaller, but not social security or Medicare wages. Social security and state unemployment each have an annual cap for each employee. This page states no dollar amount for a cap.
Does a provider pay the taxes? The provider calculates the pay. Northbrook deposits the federal taxes itself. Level 6 shows the case where the provider pays the taxes.

The card's own read-back sample is a UK one, with PAYE. For this US example, the skill reads back the scope and waits for a yes:

“I will reconcile payroll for Northbrook Trading for the quarter that ended on 30 September 2026: register, GL, bank and filings. I will use the files you uploaded. They are the provider register for 4 runs, the GL detail, and trial balances at 30 June and 30 September. They also include the bank statement for July to September, the remittance records and the Q3 Form 941 as filed. Federal deposits are due on the 15th of the next month, 401(k) money on the 7th, and state unemployment each quarter. You stated the wage bases. Shall I go ahead?”

The read-back never repeats the line of one employee.

Learning path

Six levels, from simple to complex

Check it yourself

Tie your own payroll quarter

Enter one period of your own, or load an example. The page runs the arithmetic of Steps 1 to 4 and Step 6 from references/method.md. It has no tax rate field, because each tax comes from your register. The page sends nothing anywhere.

The payroll register I have the register Gross wages Federal income-tax wages Income tax withheld Employee social security and Medicare Pre-tax deductions Employer costs

The books (general ledger) Payroll expense, all accounts Capitalised labour Accrued wages, closing less opening Employer cost expense Manual entries, no payroll run Net pay on the payroll journal (used with no register) Net pay disbursed, as recorded

The bank I have the bank statement Net pay that left the bank Outstanding items (checks not cashed)

The filing and the date Total tax on the filing Tax credited to tax liabilities in the GL Wages subject to income tax on the filing As-at date (period end)

Liability	Opening	Accrued	Remitted	GL closing	Unpaid part	Its due date

Net pay is gross wages less income tax, employee social security and Medicare, and pre-tax deductions. The bridge is register gross, less capitalised labour, plus accrued wages and manual entries. Each liability is opening plus accrued less remitted. The page counts days past due in calendar days, from the due date to the as-at date. Enter a due date for each unpaid part, or the overdue flag cannot be raised. A correction from this page is a proposal. A person decides and posts it.

Using it

What it asks, needs and gives back

Asks firstNine things, in one message. Use MosoFin, or upload the data? Which entity, and does one payroll service run several entities? Which period? Then the payroll registers with the off-cycle runs, the bank statement and the remittance records. Then the due date of each liability, the wage base rules for each tax, and whether a provider pays the taxes.

NeedsThe registers, the GL activity and both period-end balances for every payroll account, the bank statement or the payment records, and the remittance records. The skill also recommends the tax filing figures and the prior reconciliation. Without the register, the skill reports Step 5 as NOT PERFORMED.

Gives backEight sheets: summary, register-to-GL bridge, net pay to bank, liability roll-forward, filing reconciliation, taxable wage base reconciliation, exceptions and corrections, and coverage. It makes the Excel file only on a yes, for example Payroll_Reconciliation_Q3-2026_Northbrook Trading.xlsx.

NeverThe skill never reads your data before your yes to the read-back. It never writes, posts or pays, and never shows the pay of one employee. It never runs a gross-based check in place of Step 5. It never reports a tie against a source that it did not get. It never guesses a due date, a wage base rule or a remittance status. It calculates no penalty.

Sources

Where every fact on this page comes from

The rules are the skill's own. The facts below come from seven outside sources: five IRS pages, an HMRC page and a section of an OpenStax textbook. 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 four-source frame, the six bridge causes and the eight sheets are the skill's own. So are the [auto], [gated] and [manual] verdicts, the NOT PERFORMED rule and the order by consequence. MosoFin made up Northbrook Trading and every figure in the examples. This page states no tax rate and no wage base cap. Every tax amount comes from Northbrook's payroll provider report.