Accounting software that won’t break at 20+ staff

Most UK founders don’t “choose accounting software”. They outgrow whatever they started with—usually right when cash is tight, hiring is accelerating, and HMRC compliance is suddenly non‑negotiable.

If you’re building a UK solopreneur business through online marketing and automation, this is the unsexy truth: your finance stack becomes a growth bottleneck long before your marketing does. The moment you add a bookkeeper, a part-time ops lead, a second bank account, multiple sales channels (Shopify + Stripe + marketplaces), or overseas customers, a basic setup starts to creak.

This post is for British startups and scaleups moving from “founder does everything” to “a real team runs the engine”. We’ll cover what to look for in accounting software for medium sized businesses (and soon-to-be medium sized businesses), the questions that protect you from painful migrations later, and a clear view of three popular UK options—Sage Accounting, QuickBooks, and Xero—through a scaling lens.

What changes when your startup becomes “medium-sized”

Answer first: When you move into the medium-sized stage, accounting stops being a monthly admin task and becomes operational infrastructure.

Early on, you can get away with invoicing, a simple P&L, and a tidy bank feed. Later, finance touches everything: pricing, hiring, inventory, marketing ROI, and cash planning. In practice, “medium-sized” isn’t just headcount—it’s complexity.

Here’s what typically changes as you scale from solopreneur to a team (and it’s especially common for UK businesses growing via digital channels):

• More transactions, more sources: Stripe, PayPal, Shopify, Amazon, Meta ads spend, Google ads, subscriptions, refunds.
• More stakeholders: You, a bookkeeper, an accountant, maybe a finance manager—each needs access without chaos.
• Tighter compliance: HMRC’s Making Tax Digital (MTD) has pushed many UK businesses toward digital records and submissions, and expectations keep rising.
• More “edge cases”: Multi-currency, partial payments, credit notes, international VAT considerations, contractor payments, project profitability.

A useful rule: If you can’t answer “how many months of runway do we have?” in under 10 minutes, your accounting system isn’t keeping up.

The non-negotiables: what medium-sized accounting software must do

Answer first: Medium-sized business accounting software must handle volume, multi-user workflows, reliable reporting, and integrations—without turning month-end into a crisis.

Most products can generate invoices. That’s table stakes. The differentiator is whether the system stays calm as your business gets noisier.

Core features you should insist on

These are the capabilities that tend to matter most for UK startups and scaleups:

1. Bank feeds + reliable reconciliation

   • Fast reconciliation is how you keep records current.
   • Look for rules, batch matching, and clean exception handling.

2. Multi-user access with permissions

   • You need separation: founders shouldn’t share logins with bookkeepers.
   • Permissions prevent accidental edits and reduce fraud risk.

3. Management reporting you’ll actually use

   • P&L and balance sheet are basics.
   • For scaling decisions, you want trend views, budget comparisons, and exportable reports for investors or lenders.

4. AR/AP workflows (getting paid + paying suppliers)

   • Late payments kill growth.
   • Strong accounts receivable tools (invoice reminders, statements, payment links) pay for themselves.

5. Multi-currency (if you sell internationally)

   • Not just “can we invoice in USD?” but “does it convert cleanly to GBP and report properly?”

6. Integrations that match your marketing and sales stack

   • If you’re running content + paid acquisition, your finance system must play nicely with payment providers and ecommerce.
   • Integration volume matters because manual posting is where errors multiply.

Snippet-worthy truth: Accounting software is only as good as its bank reconciliation and reporting. Everything else is a nice-to-have.

When “free” accounting costs you more

Answer first: Free tools often monetize data, limit support, or create migration pain right when you can least afford disruption.

For sensitive financial data, paying is usually sensible. Apart from trust and support, the bigger cost is switching later: re-training staff, re-mapping charts of accounts, re-connecting apps, and cleaning historical data.

The subscription model has a trade-off too: you get continuous updates (and MTD-related improvements), but your long-term cost can exceed a one-off licence. That’s fine—if you’re buying time and stability.

The 4 supplier questions that save you from a bad decision

Answer first: Ask about backups, support response, proof with similar clients, and multi-currency handling before you sign.

These are the questions worth asking every accounting software supplier (or partner) before you commit:

1. How is data backed up, and how quickly can it be restored? If something goes wrong, you need a clear recovery story.

2. What does customer support look like in real life? Ask:

   • Support hours (UK business hours matter).
   • Typical response time.
   • Escalation path for urgent issues around VAT deadlines or payroll runs.

3. Who like us is using it successfully? “Similar” means similar transaction volume, similar channels (ecommerce vs consultancy), and similar team size.

4. How does it handle foreign currency payments into GBP? Multi-currency is where “it technically works” can still mean messy reporting.

If a vendor can’t answer these crisply, you’re not buying software—you’re buying future friction.

A practical shortlist: Sage vs QuickBooks vs Xero (UK view)

Answer first: Sage is strong for straightforward functionality and scaling controls, QuickBooks is integration-friendly, and Xero suits multi-user SMEs that want a broad ecosystem.

Below is a founder-friendly comparison based on UK positioning, typical strengths, and where each can frustrate you.

Sage Accounting: best when you want straightforward functionality

Sage’s cloud accounting offering is built for growing businesses that want core finance operations handled without drama. For many UK companies, Sage also feels familiar—which matters when you’re hiring finance help.

You’ll like Sage if:

• You want solid core accounting: general ledger, AP/AR, purchasing, and order management.
• Reporting matters and you want a more “business finance” feel.
• You expect to scale processes (not just invoice volume).

Watch-outs:

• Some users find the dashboard less intuitive.
• It can be pricier, and performance can struggle with very large datasets.

Pricing context (ex VAT, from the source): plans include tiers such as Standard and Plus, with AI receipt capture allowances that may affect total cost if you process lots of receipts.

QuickBooks: best for app integrations and getting set up fast

QuickBooks is popular with UK founders because it’s approachable and plugs into a big range of tools. If your growth engine is built on marketing automation—email platforms, payment tools, ecommerce—QuickBooks’ integration breadth can reduce manual work.

You’ll like QuickBooks if:

• You rely on a varied stack (payments, CRM, email marketing, ecommerce, subscriptions).
• You want a user experience that a non-finance founder can run.
• You value onboarding support to get going quickly.

Watch-outs:

• Some plans can feel limiting as you become a larger SME.
• Bank connection issues and support complaints come up in reviews—test your bank feeds early.

Pricing context (ex VAT, from the source): QuickBooks often runs UK promotions (e.g., discounted first months). Be careful comparing “intro” pricing vs true ongoing cost.

Xero: best for multi-user SMEs and scaleup collaboration

Xero is a common choice once a founder stops being the only operator in the business. It tends to suit companies where multiple people touch the books—sales ops, ops, finance, and an external accountant.

You’ll like Xero if:

• You need multiple users and clean collaboration.
• You want a large marketplace of add-ons (payments, ecommerce, reporting).
• You value strong customer support feedback.

Watch-outs:

• Starter tiers can be restrictive.
• Some menus/reporting workflows can feel clunky.
• Multi-currency is tied to higher tiers, so international selling can push you up the pricing ladder.

Pricing context (ex VAT, from the source): tiers run from entry plans up to Ultimate, with multi-currency usually not available at the lowest level.

A simple stance: Pick the system you can still live with when you’re doing 10× today’s transactions with 3× today’s team.

How to choose based on your growth path (not your current pain)

Answer first: Choose accounting software by mapping your next 12–24 months of complexity: team size, channels, currency, and reporting needs.

Most companies choose based on today’s frustration (“invoicing is messy”). Better choices come from tomorrow’s reality.

Use this 12–24 month forecast checklist

Write down your likely situation by end of 2026:

• Users: How many people need access? (Founder + bookkeeper + accountant + ops?)
• Sales channels: Direct invoices, ecommerce, marketplaces, subscriptions?
• Transaction volume: Rough monthly count (200 vs 2,000 changes everything).
• International: Any non‑GBP invoicing or foreign supplier payments?
• Stock: Do you need stock tracking, purchase orders, or simple “sales-only” accounting?
• Reporting cadence: Monthly board pack? Investor updates? Loan applications?

Then choose software that meets the future requirements natively, without Frankenstein add-ons.

A quick “fit” guide

• Service business / agency scaling from solopreneur: Prioritise reporting, time/project profitability, and clean invoicing workflows.
• Ecommerce brand growing via paid social: Prioritise integrations (Shopify/Stripe), inventory/COGS visibility, and reliable reconciliation.
• B2B SaaS moving upmarket: Prioritise multi-entity readiness (if relevant), revenue recognition support via integrations, and audit trails.

Migration tips: how to switch without breaking month-end

Answer first: The safest accounting software migration is staged: run parallel reporting, lock your chart of accounts early, and migrate at a clean period boundary.

If you’re already on a basic tool and feeling the strain, switching can be smooth—if you treat it like a project, not an admin task.

A sensible migration plan (founder-friendly)

1. Pick a clean cutover date End of month or end of quarter works best. Avoid VAT deadline weeks.

2. Standardise your chart of accounts Don’t bring chaos into a new system. Decide categories you’ll want to report on (e.g., separate paid social vs content spend).

3. Reconnect your “money pipes” first Bank feeds, Stripe, PayPal, Shopify. If these aren’t stable, nothing else matters.

4. Run one month in parallel Reconcile both systems for a month to catch mapping errors.

5. Document the workflow Write a one-page SOP: who raises invoices, who approves bills, when reconciliation happens, and how files are stored.

For marketing-led solopreneurs turning into teams, that SOP is gold. It’s part of operational maturity, like having a content calendar.

The hidden win: better accounting makes your marketing smarter

Answer first: When your accounting system is clean, you can tie marketing spend to cash reality—runway, payback periods, and profitability—without guesswork.

This fits the broader UK Solopreneur Business Growth theme because growth isn’t just traffic and followers. It’s also whether the business can absorb demand without financial confusion.

Once reconciliation and reporting are reliable, you can make sharper calls:

• Increase ad spend because cash collection is predictable.
• Spot which channel has the worst refund rate.
• Separate founder “nice-to-have tools” from true cost of acquisition.
• Build a monthly “marketing performance + finance” rhythm your team can run without you.

If you’re planning to scale this year, treat accounting software like you treat your website: a platform you’ll build on, not a cost you minimise.

What would change in your growth plans if your numbers were accurate, current, and visible every week—not just at year-end?