month-end-close

---
name: month-end-close
description: Works your bank lines against your invoices and receipts, then lists what reconciles, what does not, and the exact unexplained differences, ready for your bookkeeper to check.
---

# Close the month and reconcile it before the accountant asks

You give me last month's bank lines, the invoices you raised and the receipts you have. You get back a close pack: what matched, what did not, and every unexplained difference to the penny.

## What it does

1. **Agree the month and confirm the books are still open.** Default to the previous calendar month. Never reconcile a month that has already been filed or signed off: ask before pulling anything, and if the answer is that it is filed, stop and say so.
2. **Collect the four piles before starting.** Bank and card lines for the month, sales invoices raised, purchase invoices and receipts, and payouts from any card machine or payment processor. If one pile is missing, name it and stop. Closing three quarters of a month and calling it closed is the failure this skill exists to prevent.
3. **Match bank lines to invoices on amount and date, allowing two days either way.** A difference under £0.50 is rounding or a fee: note it and move on. A difference of £0.50 or more is a flagged variance and the delta gets printed next to it. These thresholds are taken from Anthropic's own month-end-prep skill.
4. **List the two kinds of orphan separately, never merged into one total.** Money into the bank with no invoice behind it (cash, a wire, a misposted transfer), and an invoice or receipt with no bank line against it (unpaid, paid to a personal account, or paid next month). The owner can act on each of those; a single "unreconciled" figure tells them nothing.
5. **Flag a suspicious duplicate only when all three agree:** the same amount within one penny, the same supplier or customer name, and posted within five calendar days of each other. Show the two records side by side with the reason they matched, and let the owner say which is real. Never void, delete or amend either.
6. **Chase a receipt for every expense over £25 that has no document.** Match a receipt to a line by amount within £0.50 and date within three days. List the ones with nothing against them. The owner can supply the file or mark it as not required, for example a monthly direct debit. Do not silently skip this step because the receipts folder was not to hand.
7. **Prove the bank balance and print the difference if it does not prove.** Opening balance plus money in minus money out must equal the closing balance on the statement. If it does not, print the exact unexplained difference in pounds and pence, and stop there. Never round it, never add a balancing line, never describe it as "small".
8. **Write the month in plain English, 150 to 250 words.** What came in and what drove it, what it cost, any expense line that moved more than 10% against the previous month with one sentence on why, and the bottom line. No jargon: if a term is not plain English, define it in the sentence.
9. **Produce the close pack and the question list.** The pack holds the reconciliation table, the two orphan lists, the flagged duplicates, the missing receipts and the plain-English summary. It ends with a numbered list of questions for the bookkeeper or accountant, each naming a date and an amount. Save it as YYYY-MM-close.

## Then it checks

1. The balance proof from step 7 appears in the pack, either as reconciled or as an exact difference. No balancing figure was invented to make it close.
2. Every unexplained difference is a line with a date, an amount and a description of what it might be. There is no lump sum standing in for several unknowns.
3. Nothing was categorised, amended, voided or deleted on the owner's behalf. Every flagged item is still sitting there waiting for a human.
4. Every flagged duplicate shows both records side by side, not just an assertion that a duplicate exists.
5. The receipts list covers every expense over £25, and separates the ones still missing from the ones the owner marked as not required.
6. The pack states, on its first page, that it is prepared for a bookkeeper or accountant to check and is not a filed set of accounts.

Any check fails: name it, redo that step once. Failed twice: say what is wrong and stop.

## Rules
- Public information only.
- Never invent a fact, a number or a quote.
- Never plug a difference. An unexplained gap is reported as a gap with its exact amount, however small, and the month is not described as closed until it is explained.
- Never change, categorise, void or delete a transaction. Flag it, describe it, wait for the owner.
- This prepares work for a bookkeeper or accountant to check. It is not accounting, tax or legal advice, and it is not a filed set of accounts. Anything affecting a tax return, VAT return or filing goes to a qualified professional before it is submitted.
- Tell the owner to keep the pack. HMRC requires a self-employed person to keep records "for at least 5 years after the 31 January submission deadline of the relevant tax year".

## Built from
- Anthropic, "Claude for Small Business", https://www.anthropic.com/news/claude-for-small-business, published 13 May 2026: names month-end close among its fifteen workflows and describes it as reconciling books against settlements, flagging what does not match, writing a plain-English P&L and exporting a close packet. That four-part shape is the shape of this skill.
- anthropics/knowledge-work-plugins, small-business plugin, month-end-prep and close-month skills, https://github.com/anthropics/knowledge-work-plugins/blob/main/small-business/skills/month-end-prep/SKILL.md, 23,911 stars: the two-day matching window, the £0.50 variance threshold, the three-part duplicate test within five calendar days, the £25 receipts threshold, the 10% month-on-month expense move, and the rule never to void or modify a transaction directly.
- openaccountant/skills, month-end-close skill, https://github.com/openaccountant/skills, 66 stars: the balance proof in step 7, its instruction that when the totals do not match you "track down every dollar of difference", and its practice of closing each bank account and card separately before combining them.
- Receiptor-AI/bookkeeping-skills, https://github.com/Receiptor-AI/bookkeeping-skills, 4 stars (a small, new repository, and we say so): its framing of the job as converting source documents into "accountant-reviewable bookkeeping outputs", aiming at "controlled bookkeeping support, not autonomous tax filing or unsupervised accounting-system mutation", which is why nothing here is auto-categorised.
- GOV.UK, "Business records if you're self-employed: how long to keep your records", https://www.gov.uk/self-employed-records/how-long-to-keep-your-records: the five-year retention rule quoted in the last rule.

Sources for month-end-close

Everything below was opened and read. Star counts were read from the GitHub API endpoint `https://api.github.com/repos/<owner>/<repo>` and are printed exactly as returned. Several of these repositories are small and new, and the counts say so plainly rather than being dressed up.

Anthropic, "Claude for Small Business"

https://www.anthropic.com/news/claude-for-small-business, published 13 May 2026.

The launch announcement for Anthropic's small business plugin. Month-end close is one of the fifteen named workflows, described on the page as: "Reconcile your books against settlements, flag what doesn't match, write a plain-English P&L, and export a close packet." That single sentence set the shape of this skill: reconcile, flag, narrate, pack. The page's stance on control, "You approve the plan first or, when you're ready, let it run end-to-end", is why every flagged item in our version waits for a human rather than being cleared automatically.

anthropics/knowledge-work-plugins, month-end-prep and close-month skills

https://github.com/anthropics/knowledge-work-plugins/blob/main/small-business/skills/month-end-prep/SKILL.md and .../skills/close-month/SKILL.md, repository star count 23,911, read from the API.

Anthropic's own shipped implementation of the workflow named on the launch page. Both skill files were read in full and they are the source of nearly every number in our version. The two-day matching window in step 3, and the rule that a difference under $0.50 is rounding or a fee while $0.50 or more is flagged with the delta, come from month-end-prep step 3. The duplicate test in our step 5 is its step 4, which flags a duplicate only when all three of amount within $0.01, same vendor or customer name, and posted within five calendar days agree. The £25 receipts threshold and the amount-within-$0.50, date-within-three-days receipt match are its step 5. The 10% month-on-month expense move in our step 8 is its P&L narrative structure, as is the 150 to 250 word length. Its approval gates gave us two of our rules: never reconcile a month that has been filed, and never void or modify a transaction directly, surface the flag and let the owner make the change.

From close-month we took the three-way split of gaps that our step 4 uses: unmatched settlements, unmatched deposits, and matched-but-different variance lines. We collapsed that to two orphan lists plus the variance flag, because an owner with no payment processor still has the same two piles.

We converted dollar thresholds to pounds at face value rather than converting currency. £25 and £0.50 are the right order of magnitude for a UK small business, and pretending to a converted precision would be false accuracy.

openaccountant/skills, month-end-close skill

https://github.com/openaccountant/skills, repository star count 66, read from the API. The repository description on GitHub opens "44 open-source financial skills for AI agents".

`business/month-end-close/SKILL.md` was read in full. Two things came from it. First, the balance proof that is our step 7: its "Without Wilson" section walks an owner through summing the month's transactions and comparing to the net change on the bank statement, and its notes insist "The reconciliation step is critical. If Wilson's total and your bank statement do not match, do not skip it. Track down every dollar of difference." That instruction is why our step 7 stops rather than continuing with a difference outstanding, and why "never plug a difference" is a rule. Second, its note that multiple bank accounts and cards should each be closed separately before a combined summary, which is why step 2 asks for bank and card lines as one pile but the proof in step 7 is run per account.

We did not take its filename convention wholesale, but our `YYYY-MM-close` naming follows its `2026-03-close.xlsx` pattern.

Receiptor-AI/bookkeeping-skills

https://github.com/Receiptor-AI/bookkeeping-skills, star count 4, read from the API. This is a very small and very new repository and the count reflects that: it is cited for one specific idea, not for popularity.

Its README describes "Open-source bookkeeping skills for AI agents" that "convert source financial documents into accountant-reviewable bookkeeping outputs", and states the aim as "controlled bookkeeping support, not autonomous tax filing or unsupervised accounting-system mutation". Two decisions here follow from that. Our pack is explicitly labelled on its first page as prepared for a bookkeeper or accountant to check, and our rules forbid auto-categorising anything. The repository also lists bank reconciliation as matching book entries against bank statements and resolving discrepancies, which confirms the orphan-list approach in our step 4 rather than reporting a single unreconciled total. One more thing came from it: its jurisdiction model keeps country-specific tax and VAT rules in separate files and tells the agent to stop at jurisdiction-neutral work and ask before applying tax-specific rules. Its active baseline is the United States, so the UK jurisdiction in our skill (the HMRC retention rule) was supplied from GOV.UK below, not borrowed from it.

GOV.UK, how long to keep your records

https://www.gov.uk/self-employed-records/how-long-to-keep-your-records

The primary source for the retention rule in our last rule, quoted exactly: "You must keep your records for at least 5 years after the 31 January submission deadline of the relevant tax year." The page also notes a different rule for very late returns, records kept for fifteen months after submission where a return is more than four years late, which is why the skill states the general rule and sends anything unusual to a professional rather than trying to cover the exceptions.

Read and dropped

Two repositories named in the brief were opened and are not cited, because citing them would have implied they contributed something they do not contain.

**The-Focus-AI/quickbooks-skill**, https://github.com/The-Focus-AI/quickbooks-skill, 16 stars read from the API. The README describes read-only access to QuickBooks Online data: querying customers, vendors, invoices and bills with date filtering and pagination. There is no reconciliation, no closing procedure and no bank matching anywhere in it. It is a data-retrieval skill, and nothing in our version came from it.

**vpodugu/startup-bookkeeper**, https://github.com/vpodugu/startup-bookkeeper, 17 stars read from the API. A conversational expense tracker with receipt OCR, a dashboard and P&L reports. Its own README rules out the thing we needed: under "What This Is Not" it states the skill is "a lightweight tracking tool, not accounting software", and that it does not do double-entry accounting or produce auditable financial statements. Honest of it, and it means it has nothing to lend a reconciliation skill.

Best public prompt we found for this job

`anthropics/knowledge-work-plugins`, `small-business/skills/month-end-prep/SKILL.md`. It is the only public artefact we found that puts real numbers on every judgement, a matching window, a variance threshold, a duplicate test with three conditions, a receipts floor, rather than telling the model to "reconcile carefully". Every threshold in our skill can be traced to a line in it.

The one line worth copying verbatim:

"Never void or modify a QuickBooks transaction directly."