How Taxolase Calculates Your Tax
Every figure Taxolase shows comes from published tax law for Thailand, United States, United Kingdom, Singapore and Australia. This page explains the rules we apply, what each estimate leaves out, and where the numbers come from — so you can check our work.
Rates and rules for tax year 2026 · Last reviewed September 19, 2026
How every calculation works
All five countries run through the same five steps, in this order. Only the numbers — brackets, allowances and caps — differ.
- 1
Gross annual income
Your salary and any bonus are combined into one annual figure. Anything that isn't a valid positive number counts as zero, so a typo can never produce a negative or infinite result.
- 2
Automatic deductions
Deductions the law gives everyone — such as Thailand's 50% expense deduction and personal allowance, the US standard deduction, or the UK Personal Allowance — are applied without you entering anything.
- 3
Your deductions, limited to the legal maximum
Each deduction you enter is capped at its statutory limit before it is used. Entering more than the law allows never gives extra benefit.
- 4
Net taxable income
Gross income minus deductions, never below zero. Deductions can reduce your taxable income to nothing, but never create a negative one.
- 5
Progressive brackets and levies
Each slice of taxable income is taxed at its own bracket's rate and the slices are added up. Flat charges that sit outside the brackets, like Australia's Medicare levy, are added on top. Every amount is rounded to the cent.
The same calculation code runs everywhere in Taxolase — the calculator, the comparison pages, the PDF report and the savings simulator — so they can never show different numbers for the same inputs.
Thailand
Thai personal income tax (PND 90/91) for a resident individual with salary income. Tax year 2026, amounts in THB.
Included in the estimate
- Progressive rates from 0% to 35% applied to net taxable income; the first ฿150,000 is exempt.
- The 50% expense deduction on employment income (capped at ฿100,000) and the ฿60,000 personal allowance, applied automatically.
- Optional allowances and deductions you enter (spouse, child, parents, insurance, provident fund / RMF, Thai ESG, social security, donations), each limited to its statutory amount.
- RMF / provident fund and Thai ESG are also limited to 30% of your income, on top of their fixed baht caps. SSF purchases stopped qualifying for a deduction from 1 January 2025, so SSF is no longer offered as a deduction.
Not included
- Income other than salary (freelance, rental, investment income) and its separate deduction rules.
- Rules that link deductions together, such as the combined ฿100,000 limit on life and health insurance, and the donation ceiling of 10% of income after other deductions — enter only what you're entitled to.
- Tax credits, withholding already paid, and any temporary government measures.
Tax brackets
| Taxable income | Rate |
|---|---|
| THB 0 – THB 150,000 | 0% |
| THB 150,000 – THB 300,000 | 5% |
| THB 300,000 – THB 500,000 | 10% |
| THB 500,000 – THB 750,000 | 15% |
| THB 750,000 – THB 1,000,000 | 20% |
| THB 1,000,000 – THB 2,000,000 | 25% |
| THB 2,000,000 – THB 5,000,000 | 30% |
| Over THB 5,000,000 | 35% |
Deductions and allowances
Applied automatically
- Expense Deduction — 50% of Income (Section 40(1))Up to THB 100,000
Salary/wage income: 50% of income, capped at ฿100,000 (per the law in effect since tax year 2017).
- Personal AllowanceUp to THB 60,000
Automatic for every taxpayer.
Entered by you
- Spouse Allowance (No Income)Up to THB 60,000
Legally registered spouse who has no income of their own.
- Child AllowanceUp to THB 30,000
The 2nd child onward, born in 2018 or later, qualifies for ฿60,000.
- Parental Support AllowanceUp to THB 30,000
Per parent, aged 60 or above, with annual income not exceeding ฿30,000.
- Life Insurance PremiumsUp to THB 100,000
Policy term of 10 years or more.
- Health Insurance PremiumsUp to THB 25,000
Combined with life insurance, must not exceed ฿100,000.
- Provident Fund / RMFUp to THB 500,000
Combined across all retirement funds, capped at 30% of income and ฿500,000.
- Thai ESG FundUp to THB 300,000
Separate from the RMF cap; up to ฿300,000 and 30% of income, for purchases from 1 Jan 2024 to 31 Dec 2026 (subject to holding-period conditions).
- Social Security Fund ContributionsUp to THB 9,000
- Charitable DonationsNo fixed cap
General donations, capped at 10% of income after other deductions and allowances.
Sources
- Revenue Department of Thailand (rd.go.th) (official)
- PwC Worldwide Tax Summaries — Thailand (cross-check)
Progressive rates (0–35%, first ฿150,000 exempt) and allowances cross-checked September 2026 against the Revenue Department (rd.go.th), PwC Worldwide Tax Summaries, and HLB Thailand; rates unchanged for 2026. Estimates only — verify against rd.go.th before filing.
United States
US federal income tax and employee FICA for single, married-filing-jointly and head-of-household filers. Tax year 2026, amounts in USD.
Included in the estimate
- The seven federal brackets from 10% to 37%, using the rate schedule for the filing status you choose (single is used until you pick another).
- The standard deduction, applied automatically — or your charitable donations instead, when they are larger (you get the bigger of the two, never both).
- Above-the-line deductions you enter — traditional 401(k), traditional IRA, HSA and student loan interest — each limited to its annual cap, taken in addition to either.
- State income tax for all 50 states and DC when you choose one, using each state's own brackets, standard deduction and exemptions, and reported separately from federal tax. Rules the source spells out precisely are modeled (for example Alabama's federal-tax deduction, Ohio's income-based exemption, Utah's credit and Wisconsin's phased-out deduction); states that don't tax wages show $0.
- Employee-side FICA payroll tax, shown separately from income tax: Social Security 6.2% on wages up to $184,500, Medicare 1.45% on all wages, and the 0.9% Additional Medicare Tax above $200,000 ($250,000 for joint filers). FICA is charged on gross pay, so your deductions don't reduce it. The summary shows take-home pay after both income tax and FICA.
Not included
- Married filing separately and qualifying surviving spouse statuses, and the different income phase-out ranges each filing status has for the IRA and student-loan deductions.
- Itemized deductions other than charitable gifts (state and local taxes, mortgage interest, medical expenses) and the income-based limits on charitable gifts.
- Local (city and county) income taxes, state payroll taxes such as disability or family-leave insurance, dependents, and most state tax credits. Each state's page and result lists what its own estimate leaves out.
- High-income rules in a few states (for example Connecticut and New York "tax benefit recapture") and Maryland's exemption phase-out.
- Self-employment tax (a self-employed person pays both halves of FICA), and payroll deductions such as pre-tax health premiums that lower FICA wages. For joint filers, the Additional Medicare Tax threshold is applied to your income alone, not your spouse's too.
Tax brackets
Single
| Taxable income | Rate |
|---|---|
| $0 – $12,400 | 10% |
| $12,400 – $50,400 | 12% |
| $50,400 – $105,700 | 22% |
| $105,700 – $201,775 | 24% |
| $201,775 – $256,225 | 32% |
| $256,225 – $640,600 | 35% |
| Over $640,600 | 37% |
Married filing jointly
| Taxable income | Rate |
|---|---|
| $0 – $24,800 | 10% |
| $24,800 – $100,800 | 12% |
| $100,800 – $211,400 | 22% |
| $211,400 – $403,550 | 24% |
| $403,550 – $512,450 | 32% |
| $512,450 – $768,700 | 35% |
| Over $768,700 | 37% |
Head of household
| Taxable income | Rate |
|---|---|
| $0 – $17,700 | 10% |
| $17,700 – $67,450 | 12% |
| $67,450 – $105,700 | 22% |
| $105,700 – $201,750 | 24% |
| $201,750 – $256,200 | 32% |
| $256,200 – $640,600 | 35% |
| Over $640,600 | 37% |
Deductions and allowances
Applied automatically
- Standard DeductionUp to $16,100
Applied automatically: $16,100 single, $32,200 married filing jointly, $24,150 head of household. Replaced by your itemized deductions only when those are larger.
Entered by you
- Traditional 401(k) ContributionUp to $24,500
Employee elective deferral limit
- Traditional IRA ContributionUp to $7,500
Deductibility phases out at higher income if covered by employer plan
- HSA ContributionUp to $4,400
Requires HDHP enrollment; self-only limit shown
- Student Loan InterestUp to $2,500
Phases out above certain MAGI thresholds
- Charitable Donations (Itemized)No fixed cap
Itemized: used only when your donations exceed the standard deduction — the calculator takes whichever is larger, never both.
Sources
- IRS — Federal income tax rates and brackets (official)
- IRS Rev. Proc. 2025-32 — 2026 rate schedules and standard deductions (official)
- Tax Foundation — 2026 State Individual Income Tax Rates and Brackets (cross-check)
- SSA — Maximum taxable earnings for Social Security (official)
- IRS — Additional Medicare Tax (Topic 560) (official)
- IRS — Social Security and Medicare withholding rates (Topic 751) (official)
- IRS — 2026 inflation adjustments announcement (official)
- PwC Worldwide Tax Summaries — United States (cross-check)
Tax rate schedules and standard deductions for single, married filing jointly and head of household are taken from IRS Rev. Proc. 2025-32 (irs.gov/pub/irs-drop/rp-25-32.pdf, Tables 1-3), re-verified September 2026; 401(k) and IRA limits from the IRS 2026 retirement-limit announcement and the HSA self-only limit from Rev. Proc. 2025-19. Federal income tax plus employee-side FICA (Social Security wage base $184,500 per the SSA; Additional Medicare thresholds per IRS Topic 560), reported separately; excludes state income tax and itemized deductions other than charitable donations. Estimates only — verify against irs.gov before filing.
United Kingdom
UK income tax at England, Wales and Northern Ireland rates. The 2026 tax year here means 2026/27. Tax year 2026, amounts in GBP.
Included in the estimate
- The 20% basic, 40% higher and 45% additional rates, applied to income after the Personal Allowance.
- The £12,570 Personal Allowance, including its taper: it falls by £1 for every £2 of adjusted net income above £100,000 and reaches £0 at £125,140. Pension contributions and Gift Aid donations you enter reduce adjusted net income, so they can restore some or all of the allowance.
- Pension contributions, Gift Aid donations and Marriage Allowance, entered as deductions up to their caps (a simplification of how relief is actually given).
Not included
- National Insurance contributions.
- Scottish income tax rates, which use different bands.
- Student loan repayments, dividend and savings income, capital gains, and the exact mechanics of pension relief at source.
Tax brackets
| Taxable income | Rate |
|---|---|
| £0 – £37,700 | 20% |
| £37,700 – £125,140 | 40% |
| Over £125,140 | 45% |
Deductions and allowances
Applied automatically
- Personal AllowanceUp to £12,570
Automatic for everyone; tapers by £1 for every £2 of income above £100,000 and reaches £0 at £125,140 — the engine applies this taper automatically.
Entered by you
- Private/Workplace Pension ContributionsUp to £60,000
Annual Allowance for tax-relievable pension contributions, 2024/25 — may be lower if you're a high earner (tapered annual allowance) or have already flexibly accessed a pension.
- Gift Aid Charitable DonationsNo fixed cap
Extends your basic rate band, giving higher/additional rate relief on the grossed-up donation amount.
- Marriage AllowanceUp to £1,260
Transfers 10% of a lower-earning spouse's Personal Allowance to a basic-rate-paying spouse or civil partner.
Sources
- GOV.UK — Income Tax rates and Personal Allowances (official)
- PwC Worldwide Tax Summaries — United Kingdom (cross-check)
England/Wales/NI rates and Personal Allowance (£12,570, tapering above £100,000) cross-checked September 2026 against gov.uk/income-tax-rates and House of Commons Library; unchanged for 2026/27 (the tax year 2026 shown here means 2026/27). Scotland uses different bands. Estimates only — verify against gov.uk.
Singapore
Singapore resident individual income tax. The 2026 tax year here means Year of Assessment 2026. Tax year 2026, amounts in SGD.
Included in the estimate
- The progressive resident rate table from 0% to 24%; the first S$20,000 is untaxed.
- Personal reliefs you enter (CPF, SRS, course fees, parent and qualifying child), each limited to its cap.
- IRAS's overall S$80,000 cap on total personal reliefs.
Not included
- One-off personal income tax rebates and other government support.
- Reliefs not listed in the calculator, and the higher SRS cap for foreigners.
- Non-resident tax rates and tax credits.
Tax brackets
| Taxable income | Rate |
|---|---|
| $0 – $20,000 | 0% |
| $20,000 – $30,000 | 2% |
| $30,000 – $40,000 | 3.5% |
| $40,000 – $80,000 | 7% |
| $80,000 – $120,000 | 11.5% |
| $120,000 – $160,000 | 15% |
| $160,000 – $200,000 | 18% |
| $200,000 – $240,000 | 19% |
| $240,000 – $280,000 | 19.5% |
| $280,000 – $320,000 | 20% |
| $320,000 – $500,000 | 22% |
| $500,000 – $1,000,000 | 23% |
| Over $1,000,000 | 24% |
Deductions and allowances
Entered by you
- CPF Contributions ReliefUp to $37,740
Relief on mandatory and voluntary CPF contributions, based on the CPF Annual Limit — Singapore Citizens/PRs only.
- Supplementary Retirement Scheme (SRS) ContributionsUp to $15,300
Singapore Citizen/PR cap; foreigners have a higher cap of $35,700.
- Course Fees ReliefUp to $5,500
For courses, seminars, or conferences leading to an approved qualification, related to your current employment or trade.
- Parent/Handicapped Parent ReliefUp to $9,000
Per dependant supported, living with you; higher cap applies for a handicapped dependant.
- Qualifying Child ReliefUp to $4,000
Per unmarried child who is dependent on you; higher relief applies for a handicapped child.
Sources
- IRAS — Inland Revenue Authority of Singapore (official)
- PwC Worldwide Tax Summaries — Singapore (cross-check)
Resident tax rate table (YA2024 onwards, top rate 24% above S$1,000,000) cross-checked September 2026 against PwC Worldwide Tax Summaries and IRAS (iras.gov.sg). The overall S$80,000 personal relief cap is applied; one-off rebates are not modeled. Tax year 2026 here means Year of Assessment 2026. Estimates only — verify against iras.gov.sg.
Australia
Australian resident income tax plus the Medicare levy. The 2026 tax year here means the 2026–27 financial year. Tax year 2026, amounts in AUD.
Included in the estimate
- Resident rates from 0% to 45%, including the reduction of the 16% band to 15% from 1 July 2026.
- The 2% Medicare levy with the single-person low-income reduction (10 cents per dollar above the threshold until the full levy applies).
- Deductions you enter — super salary sacrifice up to the concessional cap, work-related expenses and gifts to deductible gift recipients.
Not included
- Family Medicare thresholds and the Medicare levy surcharge.
- Tax offsets such as the Low Income Tax Offset, and HELP/HECS repayments.
- Non-resident and working-holiday-maker rates.
Tax brackets
| Taxable income | Rate |
|---|---|
| $0 – $18,200 | 0% |
| $18,200 – $45,000 | 15% |
| $45,000 – $135,000 | 30% |
| $135,000 – $190,000 | 37% |
| Over $190,000 | 45% |
Deductions and allowances
Entered by you
- Super Salary Sacrifice / Voluntary Concessional ContributionsUp to $30,000
Annual concessional contributions cap (indexed; $30,000 at last verification), inclusive of employer Super Guarantee contributions.
- Work-Related ExpensesNo fixed cap
Deductible only for the work-related portion, with records kept (e.g. a logbook or diary) per ATO substantiation rules.
- Charitable Donations (Deductible Gift Recipients)No fixed cap
Gifts of $2 or more to an organisation registered as a Deductible Gift Recipient (DGR).
Sources
- Australian Taxation Office (ato.gov.au) (official)
- PwC Worldwide Tax Summaries — Australia (cross-check)
Resident rates for 2026–27 (16% bracket reduced to 15% from 1 July 2026; 14% from 1 July 2027) cross-checked September 2026 against PwC and ATO-derived sources. Includes the 2% Medicare levy with the single-person low-income reduction (A$28,011 threshold for 2025-26, the latest figure verified; 10c per dollar shade-in); excludes family thresholds, offsets such as LITO, and the Medicare levy surcharge. Estimates only — verify against ato.gov.au.
How the savings estimates work
The Smart Advisory and the RMF / Thai ESG simulator answer “what would I save?” by running the same calculation twice: once with your current numbers and once with the extra contribution added. The saving is the difference between the two tax bills.
Because it recalculates rather than multiplying by a single rate, the result stays correct when a large contribution pulls part of your income into a lower bracket. The amount you can add is limited to what the law still allows given what you already claimed — for Thai RMF and Thai ESG that includes the 30%-of-income rule.
Savings shown are estimates of this year's tax only. Funds such as RMF and Thai ESG carry minimum holding periods, and selling early can cost you the tax benefit. Investments can lose value; nothing here is investment advice.
Accuracy, limits and corrections
We check each country's rates and allowances against the tax authority's published figures and at least one independent reference, and re-check them whenever a new tax year's rules are announced. The calculation code is covered by automated tests that compare results against hand-worked examples, including bracket edges and extreme inputs.
Taxolase is not a tax adviser, accountant or law firm, and an estimate is not a tax return. For anything you will file or pay, confirm the figures with your tax authority or a qualified professional.
Spotted something out of date or wrong? Please tell us at contact@taxolase.com with the country, the figure and a link to the official source — we'll review it promptly. Read our full disclaimer.
Common questions
Is Taxolase tax advice?
No. Taxolase produces estimates for information and planning. It is not a tax return, and it isn't a substitute for a qualified tax professional or your tax authority. See our disclaimer for details.
Why might my result differ from my actual tax bill?
Real returns include items an estimate can't know: other income, credits, withholding, timing, residency and local rules. Each country's “not included” list below shows what we leave out.
How is monthly income turned into a yearly figure?
Monthly salary is multiplied by 12 and stored as one annual amount, added to any yearly bonus. Switching between Monthly and Annual only changes how the number is displayed, never the result.
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