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Accounting · head to head

IRIS KashFlow vs Mercury

IRIS KashFlow logo

IRIS KashFlow

Accounting

Online accounting software for UK sole traders and small businesses

From
£13.5/month
Rated
-
Full reviewWebsite
Mercury logo

Mercury

Accounting

Banking for startups

From
Free
Rated
-
Full reviewWebsite

The short version

  • Only Mercury has a free tier, so it costs nothing to try first.
  • 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; Mercury treasury access requires a $250,000 balance held with Mercury
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which IRIS KashFlow and Mercury actually diverge.

Attributes where IRIS KashFlow and Mercury differ
AttributeIRIS KashFlowMercury
Starting price£13.5/monthFree
Pricing modelsubscriptionfreemium
Free tierNoYes
PlatformsWebWeb, Ios, Android
FoundedUnknown2019

Identical on both: 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 Mercury does not also cover.

Only in Mercury

  • Business checking
  • Savings accounts
  • Virtual cards
  • Team management
  • API access
  • QuickBooks
  • Xero
  • Stripe

What people use each for

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

IRIS KashFlow

  • business accountingnot Mercury
  • invoicing and billingnot Mercury
  • VAT managementnot Mercury

Mercury

  • Business banking and payments for startupsnot IRIS KashFlow
  • Managing treasury, invoicing and corporate cards from one accountnot 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

Mercury

  • Treasury access requires a $250,000 balance held with Mercury
  • Non USD international wires carry a 1% conversion fee
  • Choosing OUR wire coding, which covers intermediary bank charges, costs $15 per wire
  • ACH invoicing is $1 per transaction on Mercury Plus and only free on the $299 a month Pro plan
  • Advanced and recurring invoicing require Mercury Plus at $29.90 a month

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

Mercury

Free
  • Mercury (Free)Free
    • ACH payments
    • Domestic wires
    • Real-time payments
  • Mercury Plus$29.9/month
    • Invoice ACH debits
    • Recurring invoices
    • Invoicing API (500/month)
  • Mercury Pro$299/month
    • All Plus features
    • Relationship manager
    • Free ACH invoice debits

Which should you pick?

Choose IRIS KashFlow if

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

IRIS KashFlow review

Choose Mercury if

  • You need business checking.
  • You want to start without paying.
  • You work on Web, Ios, Android.
  • You also want savings accounts.
Mercury review

Questions people ask

Is IRIS KashFlow or Mercury better?
Neither clearly leads. IRIS KashFlow starts at £13.5/month and Mercury at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, IRIS KashFlow or Mercury?
Mercury has a free tier; the other does not. Paid plans start at £13.5/month for IRIS KashFlow and Free for Mercury.
Does IRIS KashFlow or Mercury run on more platforms?
IRIS KashFlow runs on Web. Mercury runs on Web, Ios, Android.
Can I use Mercury for free?
Yes. Mercury has a free tier, so you can try it without paying. IRIS KashFlow starts at £13.5/month.
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 Mercury is typically brought in for.
What can IRIS KashFlow do that Mercury cannot?
Mercury covers Business checking, Savings accounts, Virtual cards, Team management.

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
Mercury: Is Mercury business banking free?

Mercury's base banking tier is free and includes ACH payments, domestic wire transfers, real-time payments, Bill Pay, and QuickBooks/Xero automations at no monthly cost.

Source
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
Mercury: What does Mercury Plus add beyond the free tier?

Mercury Plus costs $29.90 per month and adds invoice ACH debits, recurring invoice capabilities, invoicing API with 500 calls per month, unlimited 1099 filings, and access to partner benefits.

Source
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
Mercury: Does Mercury charge monthly account fees?

No, Mercury states there are no minimum account balance requirements, overdraft fees, required monthly fees, or account opening fees. The free tier includes essential business banking, with paid tiers available for additional features.

Source
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