UK Tax Toolbox
SaaS Founder Tax Calculator UK
Use this calculator to estimate UK tax on software income before deciding whether you need sole trader or limited company advice.
UK Tax Toolbox
SaaS Founder Tax Calculator UK
Estimate tax for SaaS revenue, software subscriptions and solo founder income.
Important income assumption
Examples: platform fees, software, postage, internet, equipment, advertising, tools or subscriptions.
Most people with low expenses compare this against actual costs. Do not claim both for the same income.
Need more context?
Read our practical UK tax guides for resellers, creators and side hustlers.
Visit tax guidesHow this guidance is reviewed
Author
Written and maintained by UK Tax Toolbox, led by founder Conor Dwyer. Calculator assumptions are checked against the public sources linked on the page.
Last reviewed
12 August 2026
Basis of guidance
Public HMRC and GOV.UK guidance, published tax thresholds and the calculator assumptions stated on each page.
Useful official references
Spot something that looks out of date? Use the contact page to flag corrections. Important tax decisions should still be checked with HMRC or a qualified adviser.
Practical calculator guidance
Using the SaaS founder estimate responsibly
This calculator models a simple individual trading activity. It is suitable for an early-stage founder operating personally, but not for revenue belonging to a limited company. Confirm the business structure first, then reconcile subscription revenue, refunds, processor fees and operating costs for the same accounting period.
Record revenue before processor deductions
Stripe, Paddle, app stores and marketplaces may deduct transaction fees, refunds, chargebacks or taxes before a payout. Start from the underlying customer revenue that belongs to the trade and record those deductions separately. Annual plans, usage charges, setup work, consulting and lifetime deals should be identified so cash receipts can be reconciled to what was earned. Keep sterling conversion records for foreign-currency settlements.
Separate founder costs from personal subscriptions
Hosting, domains, databases, monitoring, email delivery, API usage, support software and contractors may be relevant business costs. A general laptop, phone, internet connection or AI subscription may also support personal projects, so document the business proportion rather than automatically claiming everything. Capital equipment, pre-trading costs and losses can require treatment beyond a simple annual expense entry.
Know when the model stops fitting
A limited company is a separate taxpayer: company revenue and expenses should not be entered as if they were the director’s sole-trader income. VAT, overseas customers, marketplace deemed-supplier rules, multiple founders, investment and retained profits also sit outside this estimate. As commercial risk or recurring revenue grows, obtain advice on structure, VAT, contracts and intellectual property rather than relying on an extraction estimate.
Worked example
A sole founder earns £18,000 from monthly subscriptions and £2,000 from setup services. Refunds are recorded against revenue; processor fees are £720, hosting and APIs cost £2,400, software costs £900 and contractor support costs £1,500. Gross trading income is £20,000 and provisional profit is £14,480. If the sales actually belong to a company, this sole-trader result is not appropriate.
Best for
- Solo SaaS founders
- Indie hackers
- Micro-SaaS owners
- Software subscription income
- No-code product founders
- AI tool builders