Should you build a custom invoicing system or use Xero?
Short answer
Most UK businesses should keep Xero or QuickBooks as the ledger in 2026 and build around it. Xero costs £18 to £70 a month ex VAT and already sends repeating invoices, Stripe pay buttons and reminders. A custom layer pays when chasing still eats staff time. Firms with 10 to 49 staff that get paid late spend 138 hours a year chasing, London Economics found in 2025. A basic custom billing system costs $8,000 to $15,000 in one 2026 vendor guide.
Deniz SancarFounder of Yarigai, London. Updated .
Yarigai is a done-for-you AI agency that builds these systems, so read this with that in mind. Every price and figure links to its source below. Read this page as Markdown.
At a glance
| Question | Answer |
|---|---|
| Xero UK list price | £18 to £70 a month ex VAT, Ignite to Ultimate (November 2026) |
| QuickBooks Online UK list price | £10 to £128 a month, 1 to 25 users (November 2026) |
| FreshBooks list price | $23 to $70 a month in USD, 5 to unlimited billable clients (November 2026) |
| Stripe fee on an invoice paid by UK card | 1.5% + 20p; Bacs Direct Debit 1%, capped at £4 |
| Time spent chasing late payers, firms with 10 to 49 staff | 138 hours a year, worth £2,337 in staff time (London Economics, 2025) |
| Small firms hit by late payment | 69% in Q1 2026 (FSB Small Business Index) |
| Custom billing system build | $8,000 to $15,000 basic, $15,000 to $35,000 mid-level (vendor guide, 2026) |
| Making Tax Digital | VAT returns, and Income Tax above £50,000 since April 2026, need compatible software |
List prices exclude intro offers. Xero and QuickBooks advertise 90% off for new customers, and FreshBooks 80% off for four months.
What Xero, QuickBooks and FreshBooks already do
All three send invoices, repeat them on a schedule and take card payments, so the real question is what they leave undone.
| Tool | Plans and list prices (November 2026) | Limits that matter for invoicing |
|---|---|---|
| Xero (UK) | Ignite £18, Grow £39, Comprehensive £55, Ultimate £70 a month, ex VAT | Ignite allows 20 invoices and 10 bills; the other plans have no invoice cap |
| QuickBooks Online (UK) | Sole Trader Plus £10, Simple Start £18, Essentials £40, Plus £60, Advanced £128 a month | 1, 1, 3, 5 and 25 users |
| FreshBooks | Lite $23, Plus $43, Premium $70 a month, USD | 5, 50 and unlimited billable clients; extra team members $11 a month each |
Xero's UK invoicing page lists most of what people picture when they think of a custom build:
- Repeating invoices that Xero creates and sends for you.
- A pay now button on online invoices, with card payments through Stripe and Direct Debit through GoCardless. Payment fees apply.
- Automatic reminders before or after the due date. Xero says it "checks your bank feeds so it only chases invoices that are still unpaid", so the reminders stop once the payment is matched.
FreshBooks includes recurring invoices and automatic late payment reminders on every plan.
A custom build earns its place when invoices start outside the ledger, when chasing needs judgement, or when one queue has to cover several companies.
What late invoices cost a UK business
Late payment costs a small firm far more than a year of any accounting plan. The best UK data is a July 2025 study by London Economics for the Department for Business and Trade, based on a survey of 1,455 businesses.
- 28% of UK businesses, over 1.5 million, are affected by late payment each year.
- Affected businesses are owed an average of £17,000 at any one time, £26 billion in total.
- Affected businesses spend an average of 86 hours a year chasing. For firms with 10 to 49 staff the figure is 138 hours, which the study values at £2,337 a year.
- Late payment closes about 14,000 businesses a year, or 38 a day, and costs the economy almost £11 billion a year.
The FSB tracks the same problem every quarter. Credit Connect's report on the FSB Small Business Index for Q1 2026 says 69% of small firms were affected by late payment. FSB's own release was not available to check.
The Small Business Protections Bill entered Parliament on 19 May 2026. It would cap payment terms at 60 days for large firms paying smaller suppliers and make interest on late payments mandatory at 8% above the Bank of England base rate.
A worked example
Take a firm with 10 to 49 staff that gets paid late. London Economics puts its unpaid invoices at £52,081 at any one time and its chasing time at 138 hours a year.
- Staff time is 138 hours at the study's £16.92 average labour cost, or £2,335 a year. The study's own figure is £2,337.
- Valued at the 8% margin the Bill sets above base rate, the cash tied up in £52,081 of late invoices costs £4,166 a year (£52,081 × 0.08).
- Together that is about £6,500 a year (£2,335 + £4,166).
Xero Grow costs £468 a year (£39 × 12), reminders included. Switch those on first. A custom layer then has to cost less than what it recovers after Xero's reminders have done their part.
What a custom invoicing build covers
A custom invoicing build in 2026 is usually a layer that creates, sends and chases invoices from the systems where the work happens, then writes everything back to Xero or QuickBooks. The usual parts:
- Recurring and usage-based invoices built from your own data, such as timesheets, job sheets or a CRM deal marked as won.
- Payment links through Stripe on every invoice. Stripe charges 1.5% + 20p for a standard UK card and 1% for Bacs Direct Debit, capped at £4. On a £2,000 invoice that is £30.20 by card or £4 by Direct Debit. Payment Links carry no extra fee, while Stripe's own invoicing product adds 0.4% per paid invoice.
- Chasers that stop when the money lands. The build listens for Stripe's payment confirmation or the bank match in Xero and cancels the next reminder.
- Chasing that reads replies. An AI step sorts answers such as "paid yesterday", "need a PO number" or "we dispute this", pauses the sequence and routes the case to a person.
- Sync into Xero or QuickBooks, so invoices, payments and contacts land in the ledger your accountant already uses.
- A debtor dashboard showing who owes what, and how late, across one company or several.
What it costs to build
No independent survey covers invoicing build costs. The figures below come from firms that sell the work.
| Build | Price | Timeline | Source |
|---|---|---|---|
| Basic custom billing system | $8,000 to $15,000 | 2 to 3 months | Techanic, April 2026 |
| Mid-level billing system | $15,000 to $35,000 | 3 to 6 months | Techanic |
| Advanced or enterprise billing system | $35,000 to $70,000 or more | 6 to 12 months or longer | Techanic |
| UK system integration, entry price | From £3,000 plus £199 a month, ex VAT | Not stated | Softomate, October 2026 |
| UK invoice extraction workflow, entry price | From £4,500 plus £299 a month, ex VAT | Not stated | Softomate |
Techanic puts annual maintenance at 15% to 25% of the build cost. On a $15,000 build that is $2,250 to $3,750 a year before hosting, against £468 a year for Xero Grow.
Why Xero or QuickBooks should stay the ledger
Keep Xero or QuickBooks as the ledger, because UK tax rules require compatible software and your accountant already works in it. A custom ledger has to rebuild both.
- HMRC says all VAT-registered businesses should now be signed up for Making Tax Digital for VAT, and must keep VAT records and submit VAT returns using compatible software.
- Making Tax Digital for Income Tax started in April 2026 for sole traders and landlords with qualifying income above £50,000. The threshold falls to £30,000 in April 2027 and £20,000 in April 2028. They must keep digital records and send quarterly updates through compatible software.
- Xero lists all four UK plans as MTD for Income Tax ready, with VAT return filing included.
HMRC links to a list of compatible software. A home-built ledger would have to become compatible software itself or pass its records into a product that is, which is the job Xero and QuickBooks already do.
The ledger is also the most expensive part to build, with bank feeds, reconciliation, VAT, payroll and year-end reports behind it. Techanic's advanced tier starts at $35,000, while Xero Ultimate costs £840 a year (£70 × 12).
The same logic applies to internal tools that replace spreadsheets and to buying versus building software more widely.
How Yarigai builds invoicing around Xero
Yarigai builds invoice chasers, receipts into Xero or QuickBooks and finance dashboards as part of its AI finance automation work. It builds inside the client's own Xero, QuickBooks and Stripe accounts, and the client owns the code, the data and the accounts from day one.
- A person approves anything that sends money, emails a customer or deletes data.
- AI and hosting bills are paid by the client at cost, and the monthly running cost is on the quote.
- Yarigai quotes a fixed price after a one-week blueprint, which is credited to the build. The blueprint puts the maths in writing, covering what the system replaces, what that costs a year and what the build costs.
- The guarantee is "If the build isn't profitable for you, we won't build it." If the build doesn't come out ahead within the first year, Yarigai doesn't take the job.
- Builds take 2 to 6 weeks, with a demo of working software every week.
For businesses that want to own their invoice documents too, Yarigai sells the source code of Yarigai Docs. It makes invoices and agreements as PDFs with e-signatures and Stripe pay links, replaces DocuSign and PandaDoc, and runs on the buyer's own Cloudflare account. Details are on the open source page.
When to build and when to stay on Xero
Use Xero or QuickBooks on their own if your invoices fit repeating templates and the built-in reminders clear most overdue accounts within a quarter of switching them on.
Build a layer around the ledger if any of these is true:
- Invoices start in another system, such as a job tracker, a timesheet or a CRM, and someone re-keys them.
- Chasing still takes hours every week after Xero's reminders are on. London Economics' figure for a firm with 10 to 49 staff is 138 hours a year, about 2.7 hours a week.
- Customers reply to reminders with questions, disputes or PO numbers that someone has to read and route.
- You run several Xero organisations and want one chasing queue across them.
A full custom ledger almost never makes sense for a business with 5 to 250 staff, because it still has to feed Making Tax Digital compatible software. For invoices that arrive rather than leave, see AI document processing.
Common questions
Can a custom invoicing system replace Xero completely?
It can, but for most UK businesses it shouldn't. VAT returns, and Income Tax for sole traders and landlords above £50,000 from April 2026, must go through Making Tax Digital compatible software. A custom system would still have to feed a product like Xero, which starts at £18 a month ex VAT.
Does a custom invoicing system work with Making Tax Digital?
Only if it passes its records into MTD-compatible software or becomes compatible software itself. The practical route is to create invoices in the custom system and write them to Xero or QuickBooks through their APIs. Xero lists all four of its UK plans as MTD for Income Tax ready.
Can Xero chase overdue invoices automatically?
Yes. Xero sends automatic reminders before or after the due date and checks bank feeds so it only chases unpaid invoices. A custom layer adds steps beyond a reminder schedule, such as reading replies, pausing on a dispute and flagging which customers to call.
How much does it cost to take card or Direct Debit payments on invoices?
Stripe charges 1.5% + 20p for a standard UK card and 1% for Bacs Direct Debit, with a 20p minimum and a £4 cap, as of November 2026. On a £2,000 invoice that is £30.20 by card or £4 by Direct Debit.
How long does it take to build a custom invoicing system?
Techanic's 2026 guide puts a basic billing system at 2 to 3 months and a mid-level one at 3 to 6 months. A layer around Xero is smaller because Xero keeps the tax, bank and reporting work. Yarigai builds in 2 to 6 weeks, and a single workflow can go live in about two weeks.
What happens to my invoice history if I build around Xero?
It stays in Xero. A layer reads and writes Xero's records through its API, so nothing needs migrating and your accountant keeps the same access.
Can I charge interest on late invoices?
Yes. The Late Payment of Commercial Debts (Interest) Act 1998 lets suppliers claim interest on late business invoices. The Small Business Protections Bill, which entered Parliament on 19 May 2026, would make interest at 8% above the Bank of England base rate mandatory. A custom chaser can add the interest line to a reminder, with a person approving it before it goes.
Sources
Checked on or before 7 November 2026. Prices change, so check the live page before you decide.
- Pricing Plans | Xero UK, Xero, checked 7 November 2026.
- Invoicing Software for Small Businesses | Xero UK, Xero, checked 7 November 2026.
- QuickBooks Pricing & Costs | QuickBooks UK, Intuit, checked 7 November 2026.
- FreshBooks Pricing, Lite, Plus and Premium Packages, FreshBooks, checked 7 November 2026.
- Pricing & Fees, Stripe, checked 7 November 2026.
- Late Payments Research: Estimating the total economic cost of late payments and their impact on the UK economy, London Economics for the Department for Business and Trade and the Office of the Small Business Commissioner, published July 2025.
- Small business confidence at risk from April cost rises, Credit Connect, reporting the FSB Small Business Index for Q1 2026, published 7 April 2026.
- Largest crackdown on late payments in over 25 years as landmark Bill enters Parliament, Department for Business and Trade, published 19 May 2026.
- Making Tax Digital for Income Tax: Quarterly update direction, HMRC, updated 27 March 2026.
- Making Tax Digital for VAT, HMRC, checked 7 November 2026.
- Billing Software Development Cost: An Expert Guide for 2026, Techanic Infotech, published 2 April 2026.
- AI Automation Pricing for UK Businesses: What Every Service Costs and What ROI to Expect in 2026, Softomate Solutions, updated 1 October 2026.
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