UK tax system – overview
UK tax year: 6 April – 5 April (NOT calendar).
Income tax is applied PAYE (Pay As You Earn) – the employer deducts from each paycheck.
Tax bands 2024-25 (England, Wales, NI)
| Band | Income | Rate |
|---|---|---|
| Personal Allowance | £0 – £12,570 | 0% |
| Basic rate | £12,571 – £50,270 | 20% |
| Higher rate | £50,271 – £125,140 | 40% |
| Additional rate | Above £125,140 | 45% |
Scotland has its own bands.
National Insurance
Additional tax:
- Class 1 employee: 8% (£12,570-£50,270), 2% above
- Class 4 self-employed: 6% (£12,570-£50,270), 2% above
- Funds state pension, healthcare, benefits
Who can recover overpayment
Common situations
- You worked only part of the tax year (started in November) – full Personal Allowance but used proportionally
- You changed jobs – emergency tax code applied (BR, OT)
- You left the UK before 5 April – unused Personal Allowance
- Multiple jobs – incorrect tax codes
- Self-employed losses
- Unclaimed work expenses (mileage, tools, uniform)
- Emergency tax codes
Emergency tax codes – flags
- BR: 20% on everything (no Personal Allowance)
- 0T: 20%/40%/45% without Personal Allowance
- M1, W1: monthly/weekly basis (no cumulative)
- K codes: prefix K – additional tax due (rare)
Standard tax code: 1257L (Personal Allowance £12,570).
Key documents
P60
End-of-year statement from employer showing:
- Total earnings for the tax year
- Total tax paid
- Total NIC paid
Issued by 31 May (after the end of the tax year on 5 April).
P45
Issued when you leave an employer. Shows:
- Income to date
- Tax paid to date
- Tax code
Gives to the next employer to set up correct tax. ALWAYS KEEP.
P11D
Shows benefits in kind (private medical, company car). Issued by 6 July.
Ways to recover overpayment
Method 1: Automatic refund (the simplest)
HMRC sometimes automatically reviews after the end of the tax year (April):
- If it sees an overpayment → sends P800 letter
- P800 = "End of Year Tax Reconciliation"
- In the letter – how to recover (online, cheque)
Method 2: Online via HMRC personal tax account
- Create an account at gov.uk/personal-tax-account
- Verify identity (Government Gateway ID + verification)
- Check "your income and tax"
- Apply for a refund if due
- Refund: bank transfer 5-10 days
Method 3: Self-Assessment
Required if:
- Self-employed earning £1,000+
- Income > £150,000
- Multiple income sources
- Foreign income
- Rental income
- High Income Child Benefit Charge
Process:
- Register for Self-Assessment (if not registered)
- You will receive UTR (Unique Taxpayer Reference) – 10 digits
- File annually before 31 January (online) or 31 October (paper) for the previous tax year
- HMRC calculates balance – refund or due
Method 4: P85 (leaving the UK)
If you are leaving the UK:
- Submit P85 to HMRC
- Form online or by mail
- Attach P45 (from last job)
- HMRC calculates refund
- Payment to UK bank account or cheque (possible overseas)
Method 5: Through a tax refund company
Companies specializing in UK tax refunds for foreign workers (especially Polish):
- Charge a 25-40% fee
- Handle the entire process for you
- Easy but expensive
- Examples: Taxback.com, RIFT, Tax Refund Now
NOTE: You do NOT need them. You can do it yourself for FREE through HMRC.
Self-Assessment – when you must
Obligation
HMRC will send a "notice to file" if you must. Or you must register yourself if:
- Self-employed (£1k+ income)
- Sole director of a limited company
- Foreign income
- Rental income
- Investment income > £10k
- High earner (£150k+)
- Capital gains
- Money from trust
Deadlines
- 5 October after the end of the tax year – register for self-assessment (if new)
- 31 October – paper return deadline
- 31 January – online return deadline + payment due
- 31 July – second payment on account due (if applicable)
Penalties
- £100 for 1-day late filing
- Daily £10 fines after 3 months
- 5% tax due after 30 days
- Plus interest on unpaid tax
Special situations
You worked only 6 months, then returned to Poland
Earnings: £20,000 in 6 months. Personal Allowance £12,570. Should pay tax only on £7,430.
PAYE may calculate "as if full year" – deducting more.
P85 or Self-Assessment recovers the difference.
Multiple part-time jobs
Each job may have a BR tax code (no Personal Allowance) – both deduct 20% on everything.
Should claim Personal Allowance on the highest-paying job – submit Self-Assessment to fix.
Self-employed Polish worker in the UK
- Register for Self-Assessment (CIS if construction)
- Pay Income Tax + Class 4 NIC + Class 2 NIC
- Claim allowable expenses (tools, vehicles, materials, accountant)
- £1,000 trading allowance (small amount – claim even without Schedule C)
Construction Industry Scheme (CIS)
Many Polish construction workers operate under CIS:
- Contractor deducts 20% (or 30% if not registered)
- You file Self-Assessment to claim a refund
- Typically ~£3-8k refund
Construction worker fixed term
Temporarily in the UK for a specific construction project – often overpay tax.
Polish student working in the UK
- Full Personal Allowance £12,570
- Student loan – check if applicable
- Often overpay if part-time work
Allowable expenses (self-employed)
- Travel (business – 45p/mile first 10k, 25p above; or actual)
- Office costs (rent share, utilities, internet)
- Tools, equipment
- Uniform, protective clothing
- Marketing, website
- Professional fees (accountant, insurance, legal)
- Training (related to existing trade)
- Business meals (limited)
How to get tax history
- Online personal tax account – history for 4 years
- Phone HMRC: 0300 200 3300
- Request P800 or P45/P60 from employer
How far back can you claim
4 years back max (extended in some cases).
So in 2025: you can claim back to the 2020-21 tax year.
Practical tips
- P60 – keep from every employer
- P45 – keep when leaving a job
- P85 – when leaving the UK
- Online tax account – best tool
- UTR – crucial for Self-Assessment
- Don't pay 25-40% to refund companies – do it yourself
- 4 years back max
- Self-Assessment 31 January online deadline
- CIS construction workers – most overpay tax
- Emergency tax codes (BR, OT) – check yours
- Tax refund average £1-3k for Polish workers
- Personal Allowance £12,570 without tax
- Clearly keep all docs for 4 years
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