Before you start

A National Insurance number
PAYE registration through your employer
A Government Gateway account, if you ever need Self Assessment
Records of foreign income and overseas accounts

Step-by-step

1
Check the tax code on your first payslip
PAYE deducts at source, so a wrong code means wrong deductions for months before anyone notices. Your code should not begin with an S — that is the Scottish prefix, and payroll run out of a Scottish head office occasionally applies it in error.
Via employerWho: YouFirst payslip
2
Learn the three English bands
A personal allowance, then Basic, Higher from £50,270 and Additional from £125,140. Three bands where Scotland has six, and a materially later Higher rate threshold. The thresholds have been frozen for several years, which quietly pulls more people into higher bands each year as wages rise.
OnlineWho: You
3
Understand the 60% trap above £100,000
The personal allowance is withdrawn by £1 for every £2 earned above £100,000, giving an effective marginal rate of about 60% between £100,000 and £125,140. Pension salary sacrifice is the standard response. It is the most consequential quirk in the English system and it is signposted nowhere.
OnlineWho: You
4
Check whether you actually need to file Self Assessment
Most employees never do — PAYE handles it. You must register if you are self-employed, have significant untaxed income, or meet one of HMRC's listed triggers. Online returns are due by 31 January following the 5 April year end.
OnlineWho: You
5
Settle your residence position in year one
The Statutory Residence Test determines UK tax residence from days present and connecting factors. The UK abolished the old non-domiciled regime and replaced it with a residence-based system, and the transitional rules are genuinely complex. If you have foreign income or assets, take advice in the first year rather than the third.
In personWho: You
6
Budget National Insurance separately from income tax
NI is charged on earnings in addition to income tax, at UK-wide rates, with an employer contribution you never see on the payslip. Any comparison that looks only at income tax understates what comes out of a UK salary.
OnlineWho: You

Documents you’ll need

National Insurance number
P60 — the annual summary from your employer
P45, if you change employer during the year
Records of foreign income and overseas accounts
Government Gateway credentials, for Self Assessment

Things most newcomers don’t know

The 60% band between £100,000 and £125,140 is the biggest hidden rate in the system.

The personal allowance is withdrawn at £1 for every £2 above £100,000, so each extra pound in that range is taxed at the 40% headline rate plus the lost allowance — around 60% in effect. A rise from £99,000 to £110,000 delivers far less than it looks like. Model it before accepting an offer in that range, and look at salary sacrifice.

Source: GOV.UK — income tax rates and personal allowances

A Liverpool salary goes further than the headline gap suggests.

Income tax and National Insurance are identical across England, so the difference between a Liverpool and a London offer is entirely on the spending side — where rents are roughly a third of central London's and most housing sits in the cheapest Council Tax bands. The take-home is what it is; the residual after housing is a different city entirely.

Source: community-reported

Frozen thresholds are a tax rise nobody voted for.

The personal allowance and the higher-rate threshold have been held flat for several years while wages rose, so each year more people cross into higher bands without any rate changing. The mechanism is called fiscal drag, and it is why your take-home percentage slips slightly each April even without a promotion.

Source: HMRC

The tax year runs 6 April to 5 April, which catches everyone once.

Almost no other country uses these dates. It decides which year your arrival income falls into, when your P60 arrives, and when Self Assessment is due. Newcomers routinely reckon against a calendar year and get their first filing wrong.

Source: HMRC

Common mistakes to avoid

Not checking the PAYE code on the first payslip, especially for a stray Scottish S prefix.
Accepting a salary between £100,000 and £125,140 without modelling the 60% effective band.
Counting the tax year as January to December rather than 6 April to 5 April.
Ignoring National Insurance when estimating take-home pay.
Assuming the abolished non-dom rules still apply to foreign income — they do not.

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.