The job costing and valuations system behind your month end

Two or three surveyors, one ledger clerk, and a month end that everything points at.

A typical business running one of these has 30 to 120 staff, somewhere between 15 and 50 live contracts, a purchase ledger clerk posting 300 to 400 supplier invoices a week, and a commercial office of two or three quantity surveyors and a commercial director who reads the CVR before anyone else does. Written in 2006 or in 2019, it does the same job, and the office runs its month end on it the same way.

In the surveyor's words, it sets up each contract with its cost codes, takes in the supplier invoices and subcontractor applications coded against them, records the monthly application for payment and what the client certified, holds the retention, deducts CIS at each subcontractor's rate, applies the VAT reverse charge where it belongs, and prints the cost value reconciliation the cost meeting argues over. The ledger clerk lives in the invoice screen. The surveyors live in the contract screen. The director reads one report.

The rules it carries are the reason nobody has replaced it:

• Retention is 5% to practical completion and 2.5% to the end of defects, except for two clients whose contracts say 3% throughout.
• CIS is deducted from everything except the VAT and the materials the subcontractor bought, at the subcontractor's verified rate, so the materials element is keyed separately and left alone.
• Since 1 March 2021 the VAT domestic reverse charge applies between VAT and CIS registered businesses unless the customer is the end user, so every contract carries an end-user flag that sets the VAT on invoices both ways.
• Prelims are spread across the contract by week from the programme, never as a percentage of value.
• A valuation is not invoiced until the payment certificate arrives, except for the one client whose application is treated as the invoice.

None of that is in a manual. It is in the code, and in the head of whoever runs month end.

Written between 2004 and 2012, usually by a contractor who had sat in a quantity surveyor's office, or by an employee who knew Access and stayed late. Microsoft Access forms over a SQL Server database, Crystal Reports for the application for payment and the CVR, and an export to Sage at month end. Extended for years afterwards: a variations screen, a retention ledger, a CIS return export. It runs on a server in the office, with the front end copied onto each surveyor's PC and the reports on the ledger clerk's.

Its last real change was the reverse charge in 2021, made in a hurry by whoever could be found, and the office has asked nothing of it since. The person who wrote it has retired or moved on, and the firm that looks after the network treats the database as outside its contract. The sites cannot see it, and the application goes out on paper or as a PDF typed into someone else's portal.

Some contractors had the ledger rebuilt between 2016 and 2022, usually by a small agency or a freelancer, as a web system in React, Angular or Node, PHP or .NET Core, or assembled in Zoho Creator or Power Apps by someone in the commercial office. The contracts screen opens in a browser, the contracts managers have a login of their own, and subcontractors upload their applications to it. From the commercial office it looked like the month-end problem had been solved.

Tax and accounts are usually what froze it. When the reverse charge arrived in March 2021 it went in as a line on the invoice layout instead of in the ledger, so the VAT return is corrected by hand every quarter. The Sage export was written for a version the business has since upgraded, and month end is back on a spreadsheet. Whoever wrote the code has moved on to other work, and the servers under it have gone years without an update. Since 2023 a few commercial directors have tried the whole thing again in an AI app builder, and those attempts tend to stall at the retention arithmetic. The browser made it look newer; underneath, it is as stuck as the Access ledger it was meant to replace.

The margin on every job before the month closes, and an application out on the day it is due.

A commercial office of three cannot hold fifty contracts in its head. The system does. Every invoice and every subcontractor application lands against a code, so when the surveyor opens a contract the cost to date is already sitting against the budget, and the CVR for the cost meeting comes from the same numbers rather than from three spreadsheets that disagree.

The valuation side keeps the cash coming. The application for payment goes out in the client's layout on the contract's due date, with the retention arithmetic done and the previous certified value carried forward. Retention is a ledger rather than a memory, so the money due back at the end of the defects period gets chased. And because CIS and the reverse charge are worked out at the point of payment, the CIS return and the VAT return both match what went to the subcontractors.

Systems like this do not fall over. They fall behind.

Month end goes through one PC. The CVR and the applications come out of Crystal Reports on the ledger clerk's machine, and the run takes most of a morning with the Access front end locked for everyone else. Underneath it the database is usually SQL Server 2016, whose updates ended in July 2026, on a Windows Server 2016 that ends in January 2027.

The sites cannot see cost to date. A contracts manager who wants to know what has been spent on a job asks a surveyor, who runs a query and emails a screenshot. Subcontractor applications arrive as PDFs and get keyed in by hand, so the figure is always a week or two behind the site.

The Sage link belongs to one version of Sage. Whichever generation wrote it, the export was made for the Sage installed at the time, as a file layout, a COM link or a call to an interface that has since changed. Each upgrade is a held breath, and the accountant keeps last month's export files in case the new one fails.

The client portals want it typed again. The larger clients now take applications through their own payment platforms, so the application the system prints gets retyped into a browser, line by line, on the due date. And from April 2029 business-to-business VAT invoices have to be electronic, which neither generation was built to send.

The same contracts and codes, in a browser, with the cost arriving the day it happens.

Cost to date on the day. The contract screen opened in a browser, on the same data, so a contracts manager on site sees what has been spent on the job without asking, and the surveyor stops emailing screenshots. The CVR runs whenever anyone wants it, in seconds rather than a morning.

Subcontractor applications straight in. The subcontractor uploads or emails the application, the system reads the lines against the order, and the surveyor approves on screen with the PDF beside each line.

Retention with dates on it. Practical completion and end of defects recorded against each contract, so the ledger says what is due back this month. The 5%, 2.5% and 3% rules move out of the code into a table the surveyors maintain.

The payment timetable, tracked. Due dates, payment notices, pay less notices and the final date for payment held against every application, the ones the business makes to its clients and the ones its subcontractors make to it, so no notice is missed in either direction. Where the client uses a portal, the application goes out in the portal's format, and invoices leave electronically, ready for April 2029.

A Sage link that survives an upgrade. The export matched to the Sage the business runs now, with last month's file kept as the comparison, so month end stops depending on last month's file.

Off the month-end PC. The database on a version that is still supported, with a backup somebody has restored, and the Crystal reports replaced one at a time, so the run no longer needs the ledger clerk's machine.

Neither the Access front end nor the 2019 screens are switched off for any of this. The system is added to, and the office moves screen by screen.

The keying and the digging: invoices coded on arrival, certificates checked against what was applied for, and questions the CVR was never built to answer.

On a job costing system AI belongs in the paperwork and the lookups, not the judgement calls. Three places:

Supplier invoices coded on arrival. At 300 to 400 invoices a week, the ledger clerk keys 60 to 80 a day: contract, cost code, lines, reverse charge or not. AI reads each PDF or photo and drafts the coding from the order and the supplier's history, and the clerk checks and posts. A couple of minutes' keying on each becomes a quick check, typically an hour and a half back on a normal day.

Payment certificates set against the application. Each of the 15 to 50 live contracts brings back a certificate a month, often with a different figure on it. AI reads the certified value and the retention deducted, sets them beside what was applied for, and lists the lines that differ. The reconciling that took the surveyors a day or two each month typically comes down to a morning.

Questions no report answers. Which contracts have retention due back this quarter? Which subcontractors were paid more than their order last month? AI answers in plain words from the ledger and lists the records behind each answer for the surveyor to check, so a question that meant a query and a spreadsheet takes a few minutes.

Not worth doing: AI forecasting the final account. The surveyor's judgement of the site and the client beats any model at this size, and the cost meeting would not trust the figure.

Every one of these reads the live ledger or writes to it, so none goes in before the ledger has a test copy and a backup somebody has restored. The assessment shows which would pay back first on the system as it stands.

Secure the database, then one process at a time, with the old screens as the fallback throughout.

1. Stabilise. The source found or recovered and matched to what the surveyors run, the database on a version that is still supported, a backup restored to prove it works, and a test copy of the whole system. This goes first because nothing can be changed safely until there is a copy that is not the live month end, and because it takes the January 2027 date off the list.
2. The CVR and cost to date in a browser. The first new piece is the one the surveyors and the contracts managers feel: the contract screen and the CVR against the same data, run beside the Crystal version until nobody opens the old one.
3. Applications and invoices captured. Subcontractor applications and supplier invoices arriving electronically, coded on the way in, approved on screen.
4. Retention, the payment timetable, the portal export, the Sage link. Each a stage, each priced on its own, each live in weeks.
5. Retire the old front end when nothing still depends on it. The last thing to go is usually an application layout one client has insisted on for years.

The assessment is from £395 + VAT, sized on a free one-hour consultation, with an exact price before you commit. For a job costing system that means a few days with the surveyors, the ledger clerk and the code, and a report with costed options and a fixed price for each. Each stage after that is priced before you commit to it. How we work, what drives the price and the payment terms each have a page, and so does each technology the system is built on: Microsoft Access, SQL Server, Sage integrations and Crystal Reports, and for the newer generation React, Angular and Node, old PHP and .NET Core. Where the system needs looking after before any of that starts, legacy software support covers it.