Side hustles are booming in 2026 — but the one thing most people overlook when they start earning extra income is tax. Whether you’re freelancing, selling on Etsy, or renting a room, HMRC and the IRS both want their cut. Here’s how to stay compliant — and keep as much of your money as possible legally.
UK Side Hustle Tax: The Basics
The £1,000 Trading Allowance
Good news for small-scale side hustlers: HMRC gives you a £1,000 tax-free trading allowance per year. If your total side hustle income is under £1,000, you don’t need to declare it or pay any tax. If it’s over £1,000, you must register for Self Assessment.
Registering as Self-Employed (UK)
Once your side income exceeds £1,000/year, register with HMRC as self-employed at gov.uk/register-for-self-assessment. You must do this by 5 October in the tax year after you started earning. Penalties apply for late registration.
UK Tax Rates on Side Income (2026)
- Up to £12,570 — 0% (Personal Allowance, shared with your main job)
- £12,571–£50,270 — 20% Income Tax + 9% Class 4 National Insurance
- £50,271–£125,140 — 40% Income Tax + 2% Class 4 NI
Important: if you already use your personal allowance at your main job, your side hustle income is taxed from the first pound at 20%+.
Expenses You Can Deduct (UK)
- Equipment and tools used for the side hustle
- A proportion of your home phone and broadband (if used for work)
- A proportion of home costs if you work from home (HMRC flat rate: £6/week)
- Professional subscriptions and software
- Marketing and advertising costs
- Mileage at 45p/mile for first 10,000 miles
US Side Hustle Tax: The Basics
Self-Employment Tax
In the US, side hustle income is subject to both income tax AND self-employment tax (15.3% on the first $168,600 of net earnings in 2026). You can deduct half of self-employment tax as an above-the-line deduction.
Quarterly Estimated Taxes
If you expect to owe more than $1,000 in federal tax from your side hustle, you must pay quarterly estimated taxes (due April, June, September, January). Missing these triggers penalties — set calendar reminders.
Expenses You Can Deduct (US)
- Home office deduction (if used regularly and exclusively for business)
- Equipment, software and subscriptions
- Vehicle mileage at 67 cents/mile (2024 IRS rate)
- Health insurance premiums (if self-employed)
- Half of self-employment tax paid
- Retirement contributions to a SEP-IRA or Solo 401(k)
The QBI Deduction (US)
If you’re a sole proprietor, you may qualify for the Qualified Business Income (QBI) deduction — up to 20% of your net self-employment income. This significantly reduces your effective tax rate. Consult a tax professional to maximise this.
Top Tax Tips for Side Hustlers
- Open a separate bank account — Keep side hustle income and expenses completely separate from personal finances
- Track every expense from day one — Use a spreadsheet or app like QuickBooks or FreeAgent
- Save 20–30% of every payment for tax — Put it in a separate pot immediately
- Keep receipts for everything — Digital copies in a folder are fine for HMRC
- Consider a pension contribution — In the UK, pension contributions reduce your taxable self-employed profit
Frequently Asked Questions
Do I need to tell HMRC about my side hustle?
If your side income exceeds £1,000/year, yes — you must register for Self Assessment and declare it. Under £1,000, the trading allowance covers you and no declaration is needed.
Can I run a side hustle while employed full-time?
Yes — check your employment contract doesn’t prohibit it (some do, particularly for direct competitors). There’s no legal restriction on having multiple income sources.
What records do I need to keep?
UK: Keep records for at least 5 years after the Self Assessment deadline. US: At least 3 years (7 if you significantly underreport income). Keep invoices, receipts, bank statements and contracts.
Related: Best Side Hustles 2026 | How to Build Passive Income
Disclaimer: The content on SavvyQuid is for informational and educational purposes only and does not constitute financial advice. Always consult a qualified financial adviser before making any financial decisions.