Software for accounting firms: the cost of one more client

An accounting firm chooses software by a criterion no other business has: it does not ask how well the system runs one business, but what it costs to add one more client to it. Everything done by hand per client multiplies by the number of clients, every month, indefinitely.

From that single criterion the whole requirement list follows, and it differs considerably from the list a company would draw up for itself.

What a practice actually needs

• **Switching between clients without signing out.** If each legal entity requires a fresh login, that is several minutes per switch, several times a day, per employee.
• **Hard data isolation.** Clients must not see one another, and that has to be a property of the system rather than the discipline of an employee.
• **Bulk operations.** Payroll, VAT returns and period close for thirty clients cannot be thirty identical manual procedures.
• **Shared code lists where it makes sense.** The chart of accounts, tax rates and statutory parameters are not maintained per client — they are maintained once.
• **Deadlines in one place.** Who has not filed VAT yet, whose payroll filing is due, which client has not sent documents — that is the practice's working screen, not a report.
• **Client access to their own data.** Every call asking for a customer statement is work the client could do themselves, given a view.

Time-valid parameters — the quiet obligation

A practice works backwards more often than anyone else: correcting a prior-year calculation, reconstructing on an inspector's request, filing late. That requires a system that stores parameters as they applied on the date the calculation concerns — tax rates, thresholds, coefficients.

A system that stores only the current value forces a manual reconstruction every time, and the result of that reconstruction cannot be verified by anyone except by doing the arithmetic again by hand. It is the most expensive quiet item in a practice's work and the least often checked at selection time.

E-invoicing and documents: where the time goes

Since supplier invoices began arriving electronically, a practice's work has shifted from entry to checking. That is good news only if the system follows the shift: a document arriving through e-invoicing should reach posting as a proposal with recognised fields, and a person should confirm or correct it.

• Receipt from the e-invoicing system per client, without downloading a file for each one by hand.
• A posting proposal with the fields the system is unsure it read correctly flagged, rather than filled in by guesswork.
• Duplicate detection before posting, because the same invoice tends to arrive both by email and through the state system.
• A record of who confirmed what, because a practice's responsibility for someone else's books has to be provable.

When the practice recommends a system to a client

The practice is also an adviser: a client outgrowing an accounting program asks their accountant what comes next. There the interests of practice and client align only if the system chosen lets both work over the same data — the client the operation, the practice the books.

The alternative is familiar and expensive: the client works in their system, the practice in theirs, and an export travels between them. Every such export is a place where books and operations diverge, and every month starts with reconciliation instead of work.

NG One has a practice mode anticipated in the tenant model from the start — multiple legal entities with hard data isolation, shared statutory parameters, and client access to their own part. That is an architectural decision rather than a setting, which is why it is worth checking before the client count grows.