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Everything on ContractorMaths in one place. Calculators, comparisons, and guides will be added here as they ship.
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- Home
- Tax year 2026/27 pillar reference, Every rate, threshold, and change for the 2026/27 contractor tax year, plus walkthroughs and what may change next
- About, Mission, editorial standards, how a calculator gets built
- How we calculate, Sources, update cadence, what we don't model
- Sources & references, Every primary publisher we cite, with direct URLs
- Glossary, 60 plain-English definitions for UK contractor terms
- Editorial standards, How content gets written, reviewed, and updated
- Contact, Email and what to write about
Calculators
All in 2026/27 tax-year rates by default.
- Take-home pay (PAYE), Salary, NI, student loans, pension, Scotland
- Inside IR35 (umbrella), Day rate to net via umbrella, with pension SS
- Umbrella vs Limited Company, Side-by-side at the same day rate
- Outside IR35 (limited company), Full Ltd money flow with salary-strategy comparison
- Dividend tax, Salary + dividends to net, with band-by-band breakdown
- Salary vs dividend split optimiser, Find the director salary that maximises take-home
- Self-employed mortgage, Borrowing capacity for contractors, sole traders, Ltd directors
- Day rate → salary, Contractor's day rate as an equivalent perm salary
- Salary → day rate, Perm salary as the equivalent contractor day rate
- Hourly ↔ day rate, Convert hourly to day rate with weekly/monthly/annual roll-ups
- VAT Flat Rate Scheme, FRS gain/loss with the LCT test and first-year discount
- Contractor pension via Ltd, Multiplier on employer pension contributions vs taking as dividend
- Salary sacrifice pension, PAYE vs umbrella side-by-side, with ER NI flow-back in umbrella mode
- Plan 2 student loan, Most common UK plan (Sept 2012 – July 2023), £29,385 threshold, multi-plan support
- Plan 1 student loan, Pre-2012 English/Welsh + all NI students, £26,900 threshold
- Plan 4 student loan, Scottish students from Sept 1998, £33,795 (highest of any undergrad plan)
- Plan 5 student loan, English students from August 2023, £25,000 frozen, 40-year write-off
- Postgrad student loan, Master's / PhD from August 2016, £21,000 at 6%, always stacks separately
- Multi-plan student loan, Combinations like Plan 2 + Postgrad with the multi-plan rule explained
- Plan 2 + Postgrad (dedicated), The most common multi-plan combo: 15% combined max rate above £29,385
- IR35 status checker, 9-question case-law-weighted checker (substitution heavy, MOO included)
Guides
Long-form explainers. Each one cites HMRC sources and embeds the relevant calculator.
- How umbrella companies work, Deduction chain, FCSA accreditation, mini-umbrella warning
- What is IR35?, The three principal tests, Chapter 8 vs Chapter 10, what to do if HMRC says you're wrong
- Setting up a limited company, Step-by-step from incorporation to first invoice, with realistic timeline and cost
- First-time contractor guide, Start-here hub for someone new to UK contracting, money, IR35, decisions, year-1 timeline
- Pension via limited company, Mechanics, worked example, £60k annual allowance, taper, practical setup
- Student loans for contractors, Five plans, the multi-plan rule, umbrella vs Ltd repayment mechanics
- Limited Cost Trader test explained, Why most contractors fail HMRC's LCT test and pay 16.5% on FRS
- Umbrella margin explained, How umbrella fees work, typical £15–£35/week range, FCSA disclosure rules, hidden charges to watch for
Comparisons
Side-by-side analysis with embedded calculators. Help you decide rather than just calculate.
- Inside vs outside IR35, What changes for the contractor, financial gap and 10-row dimension table
Worked examples
Concrete scenarios with every line of the maths shown, useful for sanity-checking your own numbers.
- £500/day outside IR35 (Ltd), Canonical Ltd contractor scenario, £69,129 net from £110k revenue
- £300/day inside IR35 (umbrella), Lower-rate umbrella contractor, every deduction line explained
- £800/day outside IR35 (Ltd), High-rate scenario showing the £100k PA-taper bite
Blog
Notes on Budget changes, IR35, umbrella warnings, and tax-planning trade-offs.
- All posts, 6 articles, newest first
- Plan 5 vs Plan 2 student loan: which is worse?, Lifetime cost comparison, who comes out ahead, OBR + IFS projections
- Autumn Budget 2025: contractor changes, Dividend rates +2pp, NI threshold freeze extended to 2031
- How the dividend allowance shrank from £5,000 to £500, Three cuts in seven years and what comes next
- How to spot a mini-umbrella tax-avoidance scheme, Warning signs, named-and-shamed register, the Loan Charge precedent
- FCSA-accredited umbrella companies in 2026, What to compare beyond the margin
- Why your umbrella payslip looks smaller than the assignment rate, Three deductions before PAYE, a £400/day worked example
Legal
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