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Accounting · head to head

IRIS KashFlow vs Modern Treasury

IRIS KashFlow logo

IRIS KashFlow

Accounting

Online accounting software for UK sole traders and small businesses

From
£13.5/month
Rated
-
Full reviewWebsite
Modern Treasury logo

Modern Treasury

Accounting

Payment operations and ledger infrastructure that sits between your product and your own bank accounts

From
On request
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: IRIS KashFlow advertised monthly prices of £1.35 (Starter) and £2.75 (Business) are a 90% promotional discount off the standard £13.50 and £27.50 rates, and the promotion is described as lasting 6 months before reverting; Modern Treasury you must already have or be able to obtain your own bank accounts with the right connectivity, so early stage companies without a banking relationship cannot use it and are pushed towards a sponsor bank model instead.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which IRIS KashFlow and Modern Treasury actually diverge.

Attributes where IRIS KashFlow and Modern Treasury differ
AttributeIRIS KashFlowModern Treasury
Starting price£13.5/monthOn request
Pricing modelsubscriptionquote

Identical on both: free tier (No), platforms (Web), user rating (Not yet rated), category (Accounting).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in IRIS KashFlow

Nothing recorded that Modern Treasury does not also cover.

Only in Modern Treasury

  • Multi-rail payment initiation
  • Bank connectivity
  • Ledgers
  • Automatic reconciliation
  • Approval workflows
  • Virtual accounts
  • Compliance tooling
  • Return and exception handling

What people use each for

The jobs each tool is most often brought in to do.

IRIS KashFlow

  • business accountingnot Modern Treasury
  • invoicing and billingnot Modern Treasury
  • VAT managementnot Modern Treasury

Modern Treasury

  • A marketplace paying out to thousands of sellers that needs a ledger its application can trust rather than reconciling a payments dashboard by handnot IRIS KashFlow
  • A lender originating and servicing loans that must track disbursements, repayments and returns against its own bank accountsnot IRIS KashFlow
  • A company that wants to move off a banking as a service provider and hold its own bank accounts after seeing sponsor banks offboard fintech programmesnot IRIS KashFlow
  • An insurer handling premium collection and claims payment across several rails with approval controls and an auditable trailnot IRIS KashFlow

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

IRIS KashFlow

  • Advertised monthly prices of £1.35 (Starter) and £2.75 (Business) are a 90% promotional discount off the standard £13.50 and £27.50 rates, and the promotion is described as lasting 6 months before reverting
  • Listed prices are in GBP plus VAT, and the platform's plans are built around UK VAT filing rather than other tax regimes
  • Annual pricing is quoted at RRP £162/year (Starter) and £291.50/year (Business) before the same promotional reduction

Modern Treasury

  • You must already have or be able to obtain your own bank accounts with the right connectivity, so early stage companies without a banking relationship cannot use it and are pushed towards a sponsor bank model instead.
  • Pricing rests on an annual minimum commitment, and companies that miss their volume forecast pay the minimum regardless, which makes the headline per-transaction rate close to irrelevant in year one.
  • Supported bank connectivity is a finite list, so if your bank is not on it you are either waiting for an integration or changing banks, which is a far larger project than adopting the software.
  • It is software over banking, not banking, so it does not solve card issuing, deposit accounts or the licensing questions that a company embedding financial products still has to answer elsewhere.
  • The ledger is genuinely good but adopting it properly means making it the source of truth for balances in your product, which is a significant application change rather than a payments integration and is where implementations run long.

Pricing, plan by plan

IRIS KashFlow

£13.5/month
  • Starter Monthly$13.5/month
    • 10 invoices
    • up to 25 bank transactions
    • single user access
  • Business Monthly$27.5/month
    • unlimited invoices
    • unlimited bank transactions
    • multi-user access
  • Starter Annual$162/year
    • 10 invoices
    • up to 25 bank transactions
    • single user access
  • Business Annual$291.5/year
    • unlimited invoices
    • unlimited bank transactions
    • multi-user access

Modern Treasury

On request
  • Modern Treasury Platform$undefined/year
    • Platform access fee covering API, dashboard, infrastructure and support
    • Usage-based fees across ACH, wires, RTP, FedNow, push to card, cheques and stablecoins
    • A single annual minimum commitment that both platform and usage fees count towards

Which should you pick?

Choose IRIS KashFlow if

Nothing in the data separates IRIS KashFlow from Modern Treasury on the points above - pick on price and on how each one feels to use.

IRIS KashFlow review

Choose Modern Treasury if

  • You need multi-rail payment initiation.
  • You also want bank connectivity.
Modern Treasury review

Questions people ask

Is IRIS KashFlow or Modern Treasury better?
Neither clearly leads. IRIS KashFlow starts at £13.5/month and Modern Treasury at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, IRIS KashFlow or Modern Treasury?
IRIS KashFlow starts at £13.5/month and Modern Treasury at On request.
Does IRIS KashFlow or Modern Treasury run on more platforms?
Both run on Web, so platform support will not decide this one for you.
What is IRIS KashFlow best used for?
IRIS KashFlow is most often used for business accounting, invoicing and billing, vat management. Of those, business accounting and invoicing and billing are not what Modern Treasury is typically brought in for.
What can IRIS KashFlow do that Modern Treasury cannot?
Modern Treasury covers Multi-rail payment initiation, Bank connectivity, Ledgers, Automatic reconciliation.

Answered from the vendors’ own pages

IRIS KashFlow: What are IRIS KashFlow's core features across all plans?

All IRIS KashFlow plans include unlimited quotes, online VAT submission, mobile app access, 50+ reports, bank feeds, receipt capture, multi-currency support, and payroll for up to 5 employees.

Source
Modern Treasury: Is Modern Treasury a bank or a banking as a service provider?

Neither. You hold your own bank accounts and it is software over them. That avoids sponsor bank concentration risk but means you need the bank relationship yourself.

IRIS KashFlow: Are there promotional discounts for new IRIS KashFlow customers?

Yes, new customers receive a 90% discount for 6 months on both Starter and Business monthly plans.

Source
Modern Treasury: What does it cost?

Not published. A platform access fee plus usage fees across rails, on an annual term with a single minimum commitment. Negotiate the minimum, not the per-transaction rate.

IRIS KashFlow: Can multiple users access IRIS KashFlow on the Starter plan?

No, the Starter plan is limited to single-user access only. Multi-user access requires the Business plan.

Source
Modern Treasury: Which rails are supported?

ACH, wires, RTP, FedNow, push to card, cheques and stablecoin payments, subject to what your bank supports.

Modern Treasury: Do we still need our own compliance programme?

Yes. KYB, KYC and transaction monitoring are included in the platform, but you are the one holding the accounts and the regulatory obligation sits with you and your bank.

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