Before you start

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

Step-by-step

1
Check your tax code in your first payslip
PAYE deducts tax at source. A wrong code means wrong deductions for months. In particular your code should not begin with an S — that is the Scottish prefix, and payroll run from a Scottish head office sometimes applies it in error.
Via employerWho: YouFirst payslip
2
Understand the three English bands
A personal allowance, then Basic, Higher from £50,270, and Additional from £125,140. Fewer bands than Scotland's five, and a materially later Higher rate threshold. The personal allowance and thresholds have been frozen for several years, which pulls more people into higher bands each year as wages rise.
OnlineWho: You
3
Know about the 60% trap above £100,000
The personal allowance is withdrawn at £1 for every £2 earned above £100,000, which produces an effective marginal rate of about 60% on income between £100,000 and £125,140. Pension contributions and salary sacrifice are the standard responses. It is the most consequential quirk in the English system and it is not signposted anywhere.
OnlineWho: You
4
Check whether you need to file Self Assessment
Most employees do not — PAYE handles it. You do if you are self-employed, have significant untaxed income, or earn above a threshold. The deadline for online returns is 31 January following the tax year, which runs 6 April to 5 April.
OnlineWho: You
5
Understand your residence position in year one
The Statutory Residence Test determines UK tax residence by days present and connecting factors. If you have foreign income or assets, take advice in your first year — the UK abolished the old non-domiciled regime and replaced it with a residence-based system, and the transitional rules are complex.
In personWho: You
6
Budget National Insurance separately
NI is charged on earnings in addition to income tax, at UK-wide rates, with a separate employer contribution you never see. Comparisons that look only at income tax understate what actually 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 jobs 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 of income 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 pay rise from £99,000 to £110,000 delivers far less than it appears to. Salary sacrifice into a pension is the standard remedy and it is worth modelling before accepting an offer in that range.

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

The Higher rate starts £6,600 later here than in Scotland.

£50,270 in England against £43,662 in Scotland, and three bands against five. Anyone earning above roughly £33,500 keeps more of it in Manchester than in Edinburgh or Glasgow. If you are weighing offers across the border, the gross salaries are not comparable and the gap widens with income.

Source: GOV.UK — Scottish income tax

Frozen thresholds are a tax rise nobody votes for.

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

Source: HMRC

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

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

Source: HMRC

Common mistakes to avoid

Not checking that your PAYE code is right, and in particular that it does not carry a Scottish S prefix.
Accepting a salary between £100,000 and £125,140 without modelling the 60% effective band.
Comparing an English and a Scottish offer on gross salary without modelling the different bands.
Counting your tax year as January to December rather than 6 April to 5 April.
Ignoring National Insurance when estimating take-home pay.

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