Capium vs KashFlow UK 2026: Which Should You Choose?

Capium and KashFlow are both UK-only cloud platforms with HMRC-recognised MTD for VAT, but they sit at opposite ends of the accounting software market. Capium is an all-in-one practice suite built for accounting firms running compliance and workflow for many clients at once. KashFlow, owned by IRIS Software Group, is a single-business cloud bookkeeping tool aimed at sole traders, contractors and small limited companies. This comparison sets out where they overlap, where they diverge, and which one fits which type of buyer.

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Quick verdict

• Capium is best for UK accounting practices in the 50 to 500 client range that want one platform covering bookkeeping, accounts production, corporation tax, self assessment, payroll and practice management on a shared client database.
• KashFlow is best for UK sole traders, contractors and small limited companies that want cheap, simple cloud bookkeeping with MTD VAT and bundled payroll for up to five employees, especially where the accountant uses IRIS.

Neither platform is positioned as the other’s direct rival. Capium competes with the IRIS suite, Karbon, Senta and CCH iFirm. KashFlow competes with Xero, QuickBooks Online, FreeAgent and Sage Accounting. They appear in the same comparison only because both are UK-only HMRC-recognised cloud tools, and because Capium-using practices often have clients who are weighing tools like KashFlow for their own books.

At a glance

Factor	Capium	KashFlow
Built for	UK accounting practices	UK small businesses and sole traders
Owner	Capium Limited (UK)	IRIS Software Group (UK)
Deployment	Cloud, hosted on Microsoft Azure	Cloud, UK-hosted
Country focus	UK-only	UK-only
Headline price	From £140/month + VAT base plan, plus modules from £20/month	From £13.50/month + VAT (Starter), £27.50/month (Business)
Pricing model	Suite base banded by client count + per-module add-ons	Flat monthly per business
Users included	Unlimited on every base plan	Single user (Starter), multi-user (Business)
MTD for VAT	HMRC-recognised, direct submission	HMRC-recognised, direct submission
MTD for ITSA	Functionality in place ahead of April 2026 mandate	IRIS roadmap commitment, check before relying on it
Corporation Tax (CT600)	Included via dedicated module, direct HMRC submission	Not included; trial balance flows to IRIS Accounts Production
Self assessment (SA100)	Included via dedicated module, direct HMRC submission	Not included; sits with IRIS Personal Tax or accountant
Statutory accounts and iXBRL	Included, direct Companies House filing	Not included
Payroll	Included module covering FPS, EPS, RTI, auto-enrolment, P60, P11D	Bundled on both plans, up to 5 employees
Practice management	Premium module: deadlines, tasks, document management, CRM	Not applicable; uses IRIS KashFlow Connect for accountants
Bank feeds	TrueLayer Open Banking, £1.50 + VAT per feed per month	Open Banking, included in subscription
Multi-currency	Yes, in bookkeeping module	Yes, on both plans
Third-party app marketplace	Smaller, accountant-focused	Smaller than Xero or QuickBooks Online
Contract	12 months, 30 days notice	Monthly or annual rolling
Free trial	Yes, free setup included	14 days, no card required

Pricing compared

The pricing structures are not directly comparable because the two products solve different problems. Capium prices a practice’s entire client portfolio plus the modules the firm uses. KashFlow prices a single business’s bookkeeping subscription. The sensible comparison is total cost of ownership for a realistic scenario.

Capium published pricing for 2025/26

Capium uses a two-part model: a base plan banded by client count, plus add-on modules priced per band. All figures exclude VAT.

Plan	Monthly base	Client capacity
Small	£140	Up to 100 clients
Medium	£280	Up to 300 clients
Large	£420	Up to 500 clients
Enterprise	Custom quote	700+ clients

Standard modules (Bookkeeping with MTD VAT, Accounts Production, Corporation Tax, Self Assessment, Payroll, MTD for ITSA, CapiSign) are priced from £20/month each on the small tier, £40/month medium, £60/month large. Premium modules (Practice Management, Company Secretarial, Time and Fees) sit at £40 to £167/month depending on band. Bank feeds via TrueLayer cost £1.50 + VAT per feed per month. The standard contract runs 12 months with 30 days notice to cancel.

KashFlow published pricing for 2025/26

KashFlow runs on two flat monthly plans. Pricing below is the published RRP, and new customers commonly see introductory discounts of up to 90% for the first six months.

Plan	Monthly RRP (ex VAT)	Annual RRP (ex VAT)
Starter	£13.50	£162
Business	£27.50	£291.50

Starter caps at 10 invoices and 25 reconciled bank transactions per month, single user. Business is unlimited and multi-user. Both include payroll for up to five employees, MTD for VAT, multi-currency, and the mobile app. A 14-day free trial is offered with no card details required.

Worked example: a practice running its own books

A sole practitioner with 50 clients buying the Capium Small base plan plus Bookkeeping with MTD VAT, Accounts Production, Corporation Tax, Self Assessment and Payroll would pay roughly £140 + (5 x £20) = £240/month + VAT. Adding Practice Management at the small-tier premium rate brings this to about £280/month + VAT, before bank feeds. With 30 connected bank feeds the all-in cost lands near £325/month + VAT, around £6.50 per client per month.

The same practitioner running their own limited company books on KashFlow Business pays £27.50/month + VAT, or £291.50/year, and that includes payroll for up to five employees. KashFlow does not file the practice’s own statutory accounts or CT600, so a practitioner using KashFlow alone would still need separate accounts production and tax filing software, which is the gap Capium fills in one package.

Worked example: a small business client

A limited company with one director, one employee, around 30 sales invoices a month and a busy current account would outgrow KashFlow Starter immediately because of the 10-invoice and 25-transaction caps. The realistic plan is Business at £27.50/month + VAT, roughly £215/year on the published annual deal, with payroll bundled. That is the realistic small-business scenario for KashFlow.

The same business sitting inside a Capium-using accountant’s stack would not buy Capium itself. Capium is licensed to the practice, not the end-business client, although the practice may grant the client access to the bookkeeping module as part of its service.

Feature by feature

Invoicing and bookkeeping

Capium provides a multi-client bookkeeping ledger built for accountants, with sales and purchase invoicing, manual journals, multi-currency, customisable nominal coding, and bank reconciliation across all clients in a unified workspace. Recurring invoices, credit notes, partial payments, customer statements, ageing reports and credit control are all covered.

KashFlow is a single-business bookkeeping tool with recurring invoices, quotes that convert into invoices, customer statements, credit limits, online payment links via IRIS Pay, Stripe, GoCardless and PayPal, and standard reconciliation. Templates are customisable but the design controls feel of an earlier generation than Xero or FreshBooks.

Verdict on this feature: different jobs. Capium is designed for an accountant working across many client ledgers; KashFlow is designed for one business owner working their own.

VAT and Making Tax Digital

Both are HMRC-recognised for MTD for VAT and submit returns directly. Both support standard, flat-rate and cash schemes, and both handle the Construction Industry Scheme domestic reverse charge for VAT.

Capium handles VAT inside the bookkeeping module across an entire client portfolio, with MTD submissions per client driven from the underlying ledger.

KashFlow has been MTD for VAT compliant since April 2019 and was an early HMRC-recognised cloud tool. Submissions go directly from inside the platform, on every plan including Starter.

For MTD for Income Tax Self Assessment, which begins to apply from 6 April 2026 to those with qualifying gross income above £50,000 from self-employment or property, Capium has functionality in place ahead of the mandate. IRIS has signalled KashFlow will support quarterly updates; sole traders should check the IRIS roadmap before relying on it for the first ITSA filing window.

Accounts production and statutory filing

Capium includes accounts production for limited companies (FRS 102, FRS 102 1A, FRS 105 micro-entity), partnerships, sole traders and charities, with integrated iXBRL tagging and direct online filing to Companies House. The trial balance flows from the bookkeeping module into accounts production without rekeying.

KashFlow does not produce statutory accounts. For an IRIS practice the route is well-established: KashFlow trial balance into IRIS Accounts Production via IRIS KashFlow Connect, then statutory accounts and CT600 from inside IRIS.

This is the structural divide between the two products and the main reason they do not really compete head to head.

Corporation tax and self assessment

Capium includes a Corporation Tax module producing CT600 returns and supporting computations with direct HMRC submission, and a Self Assessment module covering SA100 and the main supplementary pages including SA103, SA104, SA105, SA108 and SA102 with direct HMRC filing. Both modules use figures from accounts production so the chain stays inside the suite.

KashFlow is a bookkeeping tool, not a tax filing tool. CT600 is handled in IRIS Accounts Production or by the accountant’s chosen tax product. Self assessment for the director sits with IRIS Personal Tax or another product. KashFlow is not a substitute for tax software.

Payroll

Capium includes a payroll module covering weekly, fortnightly, four-weekly and monthly pay runs, RTI submissions (FPS and EPS), payslips, P60s, P45s, year-end reporting, P11D handling, statutory payments (SSP, SMP, SPP, ShPP, SAP), holiday pay, salary sacrifice, and full auto-enrolment with eligibility tracking and contribution calculations. Multi-employer payroll is supported, which matters for bureau-style practices running payroll for many client companies.

KashFlow bundles payroll for up to five employees on both Starter and Business at no extra cost. It handles PAYE, NIC, statutory pay, pension submissions to NEST and the Pensions Regulator, and end-of-year reporting. For larger payrolls IRIS sells separate payroll products and a managed bureau service.

For one small business doing its own payroll, KashFlow’s bundled payroll is one of the clearer pricing wins against Xero and QuickBooks Online, both of which charge separately. For a practice running payroll for many clients, Capium’s multi-employer payroll module is the appropriate tool.

Practice management

Capium includes a Practice Management premium module with a deadline calendar pulling statutory dates from each client’s record, task management with reminders, document management, customisable client communications, timesheets feeding the Time and Fees module, and a built-in CRM for client and prospect data. CapiSign provides e-signature for engagement letters, accounts approval and tax return approval.

KashFlow is not a practice management tool. For accountants, the practice layer comes from IRIS KashFlow Connect, IRIS Elements and Senta in the IRIS suite.

Reporting

Capium reports across all modules with the trial balance, P&L, balance sheet, VAT analysis, ageing reports and standard practice dashboards. Reporting depth in some modules has been described by users as less polished than the equivalent in Sage or IRIS.

KashFlow offers around 50 standard reports covering P&L, balance sheet, trial balance, aged debtors, aged creditors, VAT, customer and supplier analysis, with CSV and PDF export. The reporting layer is functional rather than rich; there is no equivalent to Xero’s analytics dashboards or QuickBooks Online’s cash flow forecasting.

Support

Capium includes free setup with every base plan and offers six-days-a-week support. KashFlow’s recent public review sentiment around support has been mixed since the IRIS acquisition, with a small Trustpilot sample showing recurring complaints about response times. Buyers should weigh published support hours alongside current customer feedback.

MTD and compliance

Both platforms are HMRC-recognised across the parts of MTD they cover. The recognised scope is different.

Capium recognised submissions:

• MTD for VAT (direct)
• PAYE RTI: FPS and EPS (direct)
• Self Assessment: SA100 and supplementary pages (direct)
• Corporation Tax: CT600 and computations (direct)
• Companies House: iXBRL statutory accounts and confirmation statements (direct)
• MTD for ITSA: functionality in place ahead of 6 April 2026

KashFlow recognised submissions:

• MTD for VAT (direct)
• PAYE RTI through bundled payroll (direct)
• MTD for ITSA: IRIS roadmap commitment, confirm timing before the first filing window

Where Capium covers the whole compliance chain inside a single suite, KashFlow covers only VAT and payroll inside the product itself. The remainder of the chain for a KashFlow user runs through their accountant’s tools, which in many cases will be IRIS Accounts Production and IRIS Personal Tax inside the IRIS suite.

For Corporation Tax, MTD for CT is not yet mandated by HMRC and no implementation date is set. Capium’s existing CT600 submission flow is the standard route inside the suite. KashFlow has no CT filing capability by design.

Integration ecosystems

Capium integrations

Bank feeds via TrueLayer Open Banking cover Barclays, HSBC, Lloyds, NatWest, RBS, Santander, Nationwide, Bank of Scotland, Halifax, plus challenger banks Starling, Monzo, Tide and Revolut. Feeds refresh once every 24 hours and are charged at £1.50 + VAT per feed per month.

The third-party app ecosystem is smaller than Xero’s or QuickBooks Online’s and is centred on accountant-facing workflows: direct Companies House filing, direct HMRC submission for VAT, ITSA, CT600 and PAYE, trial balance import from QuickBooks, Sage and Excel, and generic CSV import across most modules. Practice tooling (multi-client dashboard, bulk actions, deadline tracking, e-signature) is part of the platform rather than third-party.

KashFlow integrations and the IRIS ecosystem

Open Banking connections cover Barclays, HSBC, NatWest, Lloyds, Santander, Bank of Scotland, RBS, plus Monzo, Starling, Tide, Revolut Business and Wise, plus credit card feeds. Bank feeds are included in the subscription. Payment processing runs through IRIS Pay, Stripe, GoCardless and PayPal.

The structural advantage KashFlow holds over standalone competitors is the IRIS ecosystem:

• IRIS KashFlow Connect sits between client books and the practice
• IRIS Accounts Production receives the trial balance for statutory accounts and Corporation Tax
• IRIS Personal Tax handles director self assessment
• IRIS Elements offers an integrated cloud accountancy suite with shared client lists
• Senta practice management ties workflow and client portals together

For an IRIS-aligned firm, KashFlow effectively becomes the client-facing bookkeeping layer in a single-vendor stack. For non-IRIS practices, this advantage is less relevant.

The third-party marketplace outside the IRIS family is significantly smaller than Xero’s 1,000-plus apps or QuickBooks Online’s catalogue. Connections exist for major payment processors, e-commerce (limited), payroll add-ons and CRM, but breadth and depth are notably narrower than the bigger players.

Pros and cons

Capium pros

• HMRC-recognised across VAT, PAYE RTI, Self Assessment and Corporation Tax with MTD for ITSA functionality in place ahead of April 2026
• Single integrated database means trial balance flows from bookkeeping into accounts production into CT600 without rekeying
• Module-based pricing lets practices buy only what they use, starting at £20/month per module on the small tier
• Unlimited user licences on every base plan, removing the per-seat cost penalty common with practice tools
• Companies House recognised supplier with integrated iXBRL filing
• Bank feeds via TrueLayer covering all major UK banks plus challenger banks
• Auto-enrolment and multi-employer payroll built in for bureau-style firms
• UK-only product focus keeps tax codes and forms current for British practices
• Free setup and onboarding included on every base plan

Capium cons

• The user interface has been reported as feeling sluggish on the client side, with longer page-load times than the market leaders
• Adding multiple modules pushes the monthly cost up quickly
• Practice management workflow lacks native Outlook or Gmail email integration of the depth Karbon provides
• Third-party app ecosystem is smaller than Xero’s or QuickBooks Online’s
• Per-client pricing scales steeply for very large firms
• Bank feed cost is itemised at £1.50 per feed per month
• Twelve-month minimum contract on the suite

KashFlow pros

• HMRC-recognised for MTD for VAT since the regime started in April 2019, direct submission on every plan
• UK-only focus with no multi-jurisdiction noise
• Payroll for up to five employees included on both plans at no extra cost
• CIS domestic reverse charge VAT support for construction sector users
• Tight fit with the IRIS practice ecosystem (KashFlow Connect, Accounts Production, Personal Tax, Senta)
• Multi-currency on both plans, including Starter
• Lower published price than Xero or QuickBooks Online on the entry tier
• Working mobile app for receipt capture and on-the-go invoicing

KashFlow cons

• The user interface feels dated compared with Xero, QuickBooks Online and FreeAgent
• Starter plan caps at 10 invoices and 25 reconciled bank transactions a month push most real businesses to Business
• Smaller third-party app marketplace than Xero or QuickBooks Online
• Reporting is functional but basic with no advanced analytics or forecasting
• Public review sentiment is mixed, with recurring complaints about support response times since the IRIS acquisition
• Mobile app ratings are weak on both iOS and Android
• No deep project profitability or job costing
• No statutory accounts, CT600 or self assessment filing inside the product

Pick Capium if

• You are a UK accounting practice in the 50 to 500 client range looking to consolidate from a stack of separate tools onto one supplier with one client database
• You want to file VAT, PAYE RTI, Self Assessment, CT600 and statutory accounts from one platform without bridging
• You want to handle MTD for ITSA in-house from April 2026 without bolting on a separate ITSA bridging product
• You want unlimited user licences across the practice without per-seat costs
• You value UK-only product focus and current British legislation over the much larger global ecosystems of Xero or QuickBooks
• You run multi-employer payroll and want a single payroll engine across many client companies
• You want a built-in practice management layer rather than a separate Karbon, Senta or AccountancyManager subscription

Pick KashFlow if

• You are a UK sole trader, contractor or small limited company that needs simple cloud bookkeeping with MTD for VAT and bundled payroll, not a practice suite
• Your accountant uses IRIS Accounts Production, IRIS Personal Tax, IRIS Elements or Senta and you want a clean client bookkeeping layer that feeds straight in
• You operate in construction and need CIS domestic reverse charge VAT support out of the box
• You want a lower headline subscription cost than Xero or QuickBooks Online and are comfortable with a smaller app marketplace
• You need multi-currency invoicing on a low tier without paying for Xero Established
• You want UK-only software with no multi-region clutter
• You run a payroll of up to five employees and would rather have it bundled than pay separately

Pick neither if

Neither tool is the right answer for many buyers. Common alternatives:

• Xero is the better pick for a growing UK SME that needs depth across project tracking, multi-currency on higher tiers, a 1,000-plus app marketplace and a modern interface. Xero plus a separate practice tool such as Karbon is the most common stack alternative to Capium for medium-sized practices.
• QuickBooks Online is the better pick for a small business wanting cash flow forecasting, project profitability and a large global app catalogue, especially where the accountant uses QuickBooks Online Accountant.
• Sage Accounting is a strong UK-focused alternative for small businesses wanting deeper management reporting than KashFlow, and Sage 50 still suits firms that prefer locally installed software with optional cloud sync.
• FreeAgent is the better pick for freelancers and contractors who want self assessment SA103 pages and dividend planning included, especially where the user banks with NatWest, Royal Bank of Scotland, Ulster Bank or Mettle (where FreeAgent is free with the business account).
• IRIS Practice Management or CCH iFirm are stronger picks than Capium for enterprise-scale practices with thousands of clients across multiple offices.
• Karbon is the better pick for a practice that runs heavily on email-driven workflow, where Capium’s practice management module lacks comparable depth.

Comparable software

Capium and KashFlow occupy different shelves of the UK accounting software market. The closest functional alternatives to Capium are the practice suites: IRIS Practice Management for established IRIS firms, Karbon for email-centric workflow, Senta as a cloud-first practice manager inside the IRIS family, AccountancyManager for compliance-heavy small firms, CCH iFirm for enterprise-scale practices, and TaxCalc Practice Manager for desktop-oriented compliance shops. On the bookkeeping side, Capium overlaps with Xero, QuickBooks Online, Sage Accounting and FreeAgent, although the comparison is uneven because those are single-business tools.

KashFlow’s nearest rivals are Xero, QuickBooks Online, Sage Accounting, FreeAgent and Clear Books, all HMRC-recognised for MTD for VAT and all targeting some overlap of sole traders and small limited companies. Pandle and Bokio are worth considering at the free or near-free end of the market if cost is the dominant factor and feature depth is not critical.

FAQs

Are Capium and KashFlow direct competitors?

Not really. Capium is a practice suite for accounting firms covering bookkeeping, accounts production, tax, payroll and practice management across many clients. KashFlow is a single-business cloud bookkeeping tool for sole traders and small companies. They share UK focus and HMRC-recognised MTD for VAT, but they sit at opposite ends of the buyer market.

Can KashFlow replace Capium for a small practice?

No. KashFlow does not produce statutory accounts, file CT600 or handle self assessment. A practice using KashFlow alone would still need separate accounts production and tax filing tools, which is the gap a suite like Capium fills.

Can Capium be used by an end client rather than a practice?

Capium is licensed to the practice, not the end-business client. The practice can grant the client access to the bookkeeping module as part of its service, but the suite is built around accountant workflows rather than business owner workflows.

Are both HMRC-recognised for MTD for VAT?

Yes. Both Capium and KashFlow are on HMRC’s published list of MTD-compatible software and submit VAT returns directly without bridging.

Which handles MTD for ITSA from April 2026?

Capium has MTD for ITSA functionality in place ahead of the 6 April 2026 mandate, covering quarterly updates and end-of-period statements. IRIS has signalled KashFlow will support quarterly updates as well; sole traders should check the IRIS roadmap before relying on it for the first filing window.

Does either include payroll?

Both do, but in different forms. Capium includes a full payroll module supporting multi-employer payroll for bureau-style practices, full RTI, P11D, auto-enrolment and statutory payments. KashFlow bundles payroll for up to five employees on both Starter and Business at no extra cost; larger payrolls move to a separate IRIS payroll product or managed bureau.

Does KashFlow integrate with IRIS Accounts Production?

Yes. IRIS KashFlow Connect lets accountants pull a client’s KashFlow trial balance into IRIS Accounts Production for statutory accounts and CT600 filing.

Which has the wider third-party app marketplace?

Both are smaller than Xero or QuickBooks Online. KashFlow’s marketplace is small and focused on payments, e-commerce and CRM. Capium’s ecosystem is built around accountant-facing workflows and direct filing to Companies House and HMRC, with imports from QuickBooks, Sage and Excel.

How long are the contracts?

Capium’s standard suite contract runs 12 months with 30 days notice to cancel. KashFlow runs monthly or annually on a rolling basis. Both offer free trials.

How do their bank feeds compare?

Both run through Open Banking and connect to the major UK high-street and challenger banks. Capium itemises bank feeds at £1.50 + VAT per feed per month; KashFlow includes feeds in the subscription.

Final summary

Capium and KashFlow are both UK-only HMRC-recognised cloud platforms, but they sell to different buyers. Capium is a practice suite that covers the full compliance and workflow chain for an accounting firm, with bookkeeping, accounts production, corporation tax, self assessment, payroll, practice management and CRM all running on one shared client database. KashFlow is a single-business bookkeeping tool that does cloud invoicing, bank reconciliation, MTD for VAT and bundled payroll for up to five employees, sitting cleanly alongside an accountant’s IRIS stack for the parts it does not cover.

For a UK practice in the 50 to 500 client range looking to consolidate suppliers, Capium is the relevant product. For a sole trader, contractor or small limited company wanting low-cost, UK-focused cloud bookkeeping with MTD for VAT and a working payroll engine, KashFlow is the relevant product. Buyers expecting a head-to-head winner are usually choosing the wrong comparison. The right question is whether the buyer is a practice consolidating its toolset (Capium territory) or a single business doing its own books (KashFlow territory). Try the Capium suite trial or the 14-day KashFlow free trial before committing to either.

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