Adsum
Adsum is a London-based fintech that builds OpenTax, an AI-assisted tax automation platform consolidating VAT, PAYE, Corporation Tax and Self Assessment for UK accountants, bookkeepers and SMB finance teams via bespoke HMRC integrations.
- Company typePrivate
- Founded2019
- HeadquartersLondon, United Kingdom
- Headcount1–10
- GTM typeB2B
- OfferingSoftware
What Adsum does
Adsum Technologies Ltd is a UK-based fintech founded in 2019 that builds OpenTax, an end-to-end tax automation platform consolidating VAT, PAYE, Corporation Tax and Self Assessment into a single view for accountants, bookkeepers and in-house finance teams. The company's core technical proposition centres on bespoke direct integrations with HMRC systems that surface real-time tax data not easily accessible through standard accounting software, paired with an AI-assisted workspace that drafts payment reminders and client summaries and provides proactive issue detection ahead of filing deadlines. Adsum is FCA-registered (number 921976) and ICO-registered (ZB071038), and operates from London with an 11-person team spanning product, engineering, growth and partnerships.
The platform integrates with the dominant UK SMB accounting and banking stack — QuickBooks, Xero, IRIS and Tide — positioning OpenTax as a portfolio-level compliance and control layer for accounting practices that manage tax obligations across many client entities. Quote-based annual SaaS subscriptions are sold sales-led through website demo booking, with named-customer testimonials from mid-market UK accounting practices (Chambers Accountants, David Howard, Darren Buckley) and SMB end-customers (IVYFASHION).
Adsum monetises across three streams: subscription SaaS revenue from accounting practices using OpenTax for VAT and broader tax workflows, transaction economics around VAT refunds and payment processing, and VAT-related financing services. Geographic scope is explicitly UK-only per the company's Terms of Use, and the most recent disclosed capital event was approximately $17.5M raised across two rounds in May 2022, led by Launchbay Capital and Episode 1, alongside D2 Fund and Kinled Holding.
Adsum firmographics
Firmographics- Name
- Adsum
- Legal name
- Adsum Technologies Ltd
- Website
- https://adsum-works.com
- Company type
- Private
- Founded year
- 2019
- Operating status
- Operating
- Headcount range
- 1–10 employees
- Short description
- Adsum is a London-based fintech that builds OpenTax, an AI-assisted tax automation platform consolidating VAT, PAYE, Corporation Tax and Self Assessment for UK accountants, bookkeepers and SMB finance teams via bespoke HMRC integrations.
- Ownership category
- akta.pro rank
Adsum industry classification
Industry- Product category
- Tax Compliance Software
- NAICS
- Software Publishers (5132)
- SIC
- Services-Prepackaged Software (7372)
- akta.pro primary industry
- Revenue Systems, E-Filing & Digital Tax Administration (BPAIADAO)
- akta.pro secondary industry
- Bill Pay, Invoicing & Payables Platforms (BPAMAFAF)
Keywords
Where Adsum is headquartered
LocationHeadquarters
- HQ city
- London
- HQ country
- United Kingdom
- HQ region
- Europe
Offices1 record
Markets served
Adsum business model
Business model- GTM type
- B2B
- Offering type
- Software
- Cost components
- Personnel, Technology or R&D, Marketing or Sales, Operations, Infrastructure
Revenue model
- Software for Practices: SaaS subscription revenue from accounting firms and bookkeepers using OpenTax for VAT, PAYE, Corporation Tax and Self Assessment management
- Transaction Economics: Revenue from refunds and payment processing around VAT lifecycle events
- VAT Financing: Financing services around VAT lifecycle events for businesses
Pricing tiers
| Model | Billing | Price |
|---|---|---|
| Subscription | Annual | Quote-based pricing for accounting firms and businesses |
Go-to-market motion1 record
Distribution channels1 record
Marketing channels3 records
Adsum product offering
Product offeringCore offering
Adsum builds and sells OpenTax, an AI-enabled end-to-end tax automation platform that consolidates VAT, PAYE, Corporation Tax and Self Assessment into a single view for UK accountants, bookkeepers and finance teams. The platform combines bespoke HMRC integrations for real-time tax data, an AI-assisted workspace for payment reminders and client summaries, and payment orchestration around VAT lifecycle events, supported by an audit-ready ledger.
Product overview
Adsum is a UK tax fintech company founded in 2019 that offers a unified platform built around AI-enabled tax technology. The primary product is OpenTax, an end-to-end tax automation platform that consolidates VAT, PAYE, Corporation Tax, and Self Assessment into a single dashboard. The platform features AI-assisted workspace capabilities, bespoke HMRC integrations for real-time tax data access, payment orchestration, and an audit-ready ledger. Adsum targets businesses, accountants, and finance professionals, helping them transform compliance friction into auditable assets.
Differentiator
Problem solved
Functional benefit
Brands
- OpenTax: End-to-end tax automation platform providing compliance, filings, and deadline management. Consolidates VAT, PAYE, Corporation Tax and Self Assessment in one view with AI-assisted workspace for payment reminders and client summaries.
Products and services
- OpenTax AI-enabled end-to-end tax automation platform that consolidates VAT, PAYE, Corporation Tax and Self Assessment into a single view with an AI-assisted workspace for payment reminders and client summaries. Provides portfolio-wide HMRC visibility for accountants and bookkeepers and an audit-ready ledger for UK businesses, accountants and finance professionals.
Quantifiable outcome
- Save 1,000+ hours annually across client portfolio
- +1 more outcomes
Companies that use Adsum
Customer profileNamed customers5 records
Segments2 records
Ideal customer profiles2 records
Adsum technology and API
TechnologyTechnology focussed Yes
API detail
- Has API
- No
- API docs
- API detail
Core technology
AI maturity
App detail
Integration4 records
AI capability4 records
Feature4 records
Adsum partnerships and signals
Strategic signalPartnerships
Three partnerships are on record, tiered core.
- QuickBookscoreAccounting software integration allowing OpenTax to pull client tax data. Featured in 'Integrated with' section on Adsum website, indicating bidirectional data connectivity for joint customers using QuickBooks for accounting.
- XerocoreAccounting software integration enabling OpenTax to access client financial data. Featured prominently in 'Integrated with' section as key accounting platform partner.
- IRIScoreAccounting software integration for IRIS customer base. Partnered with and trusted by industry leaders section features IRIS as key integration partner.
Scale indicators3 records
Recent moves5 records
Expansion highlights4 records
Adsum competitors and assessment
Company assessmentDirect peers
- Avalara: Avalara is a global tax compliance automation platform covering VAT, sales tax, and related filings. It is the most directly comparable scaled competitor to OpenTax's tax-compliance-plus-payments concept, though Avalara operates across many jurisdictions rather than a single HMRC-centric stack.
- Clear Books: Clear Books is a UK cloud accounting and VAT compliance platform built specifically for small businesses and accountants. It is comparable to Adsum in market focus (UK-only), customer base (accountants and SMBs), and category (cloud accounting + HMRC compliance).
- Capium: Capium is a UK cloud practice management and accounting software suite for accountants and bookkeepers. It is comparable to Adsum in target customer (UK accounting practices) and core value proposition (consolidating compliance workflows), making it a head-to-head competitor in the practice segment.
Broad incumbents
- Sage: Sage is a UK-headquartered incumbent in accounting, payroll, and compliance software for SMBs and practices. It overlaps with OpenTax in UK tax compliance and HMRC-adjacent workflows, but as part of a much broader portfolio of products.
- FreeAgent: FreeAgent is a UK cloud accounting platform (acquired by NatWest) targeting SMBs and their accountants. It overlaps with OpenTax on UK VAT and Self Assessment workflows, though it does not offer HMRC-agent-level consolidated views.
- IRIS Software Group: IRIS is a large UK practice and payroll software incumbent and an existing integration partner of Adsum. It is comparable as a broad accounting-platform incumbent serving the same UK accountant and SMB customer base that Adsum targets.
Emerging players
- Bokio: Bokio is an emerging UK/Swedish cloud accounting and tax-filing platform for freelancers and SMBs. It is comparable to Adsum on AI-assisted accounting workflows and direct tax authority integrations, though it targets a different (smaller) end of the market.
- TaxScouts: TaxScouts is a UK tax services platform that connects individuals and SMBs with accountants for Self Assessment and corporation tax filing. It is comparable as a UK tax-tech player targeting simplification of HMRC workflows, though it is consumer-facing rather than practice-facing.
- AccountancyCloud: AccountancyCloud is a UK cloud accounting and outsourced finance platform for SMBs and startups. It is comparable to Adsum on cloud-delivered UK accounting automation, though its primary monetisation is outsourced bookkeeping rather than software.
Regional players
- TaxJar: TaxJar is a US sales-tax automation and filing platform owned by Stripe. It is comparable to Adsum on the tax-compliance-plus-payments category mechanics, but operates exclusively in the US sales-tax domain rather than UK VAT/PAYE/CT.
Market position
Strengths5 records
Weaknesses5 records
Competitive moat4 records
Key risks6 records
Key highlights7 records
Customer concentration
Adsum social profiles
Digital presenceAdsum compliance and trust
Trust signalCompliance4 records
Adsum financial estimates
Financial estimateRevenue estimate
Valuation estimate
Adsum leadership team
Management profileNumber of profiles
Profiles12 records
Adsum funding detail
Funding detailFunding overview
Funding rounds2 records
Investors4 records
Funding detail is available on the Subscription and Enterprise plan.Contact sales →
Adsum M&A and investment
M&A and investmentM&A
Investments
M&A and investment is available on the Subscription and Enterprise plan.Contact sales →
Frequently asked questions about Adsum
What does Adsum do?
Adsum builds and sells OpenTax, an AI-enabled end-to-end tax automation platform that consolidates VAT, PAYE, Corporation Tax and Self Assessment into a single view for UK accountants, bookkeepers and finance teams. The platform combines bespoke HMRC integrations for real-time tax data, an AI-assisted workspace for payment reminders and client summaries, and payment orchestration around VAT lifecycle events, supported by an audit-ready ledger.
Is Adsum a public or private company?
Adsum is a private company. It is classified as venture growth investor backed and is currently operating.
When was Adsum founded?
Adsum was founded in 2019. It employs 1 to 10 people.
Where is Adsum based?
Adsum is headquartered in London, United Kingdom, in the Europe region.
How does Adsum make money?
Three revenue lines are on record. Software for Practices are the primary driver. The others are transaction Economics and VAT Financing.
Who are Adsum's main competitors?
Direct peers on record are Avalara, Clear Books and Capium. Broad incumbents are Sage, FreeAgent and IRIS Software Group. Emerging players are Bokio, TaxScouts and AccountancyCloud. TaxJar is listed as a regional player.
Does Adsum have an API?
No public API is recorded for Adsum.
What industry is Adsum in?
Adsum's product category is Tax Compliance Software. Its primary akta.pro industry code is BPAIADAO, Revenue Systems, E-Filing & Digital Tax Administration, with a secondary code of BPAMAFAF, Bill Pay, Invoicing & Payables Platforms. Its NAICS code is 5132 and its SIC code is 7372.