The purpose of this page is two ideas in one ladder: the arithmetic reason the first £100,000 is the hardest (and why every one after it comes faster), and the real UK tax thresholds that make each milestone more than a round number.
One illustration: £6,000 a year saved, growing at 5% a year (nominal, illustrative, not a promise). The first £100,000 takes twelve years. The fifth takes three. Same saver, same habit, same rate.
The reason is visible in one comparison: at £100,000, growth at 5% contributes £5,000 a year, nearly matching the £6,000 of new saving. From that point the money is roughly a second saver working alongside the first. At £200,000 the growth is £10,000 a year and the new saving is the junior partner. Nothing about the saver changed; the share of progress done by compounding did. That is the honest version of why "the first £100k is the hardest": it is the only one built almost entirely from contributions.
Milestones are psychology, but several of them coincide with actual UK rule boundaries. Crossing these changes the tax mechanics, not just the mood. All figures 2026/27.
| Threshold | The rule | What crossing it changes |
|---|---|---|
| ≈ £22,000 in cash savings | Personal Savings Allowance: £1,000 of interest tax-free at basic rate | At an illustrative 4.5% interest rate, roughly £22,200 of cash fills the basic-rate allowance (£11,100 at the higher-rate £500). Beyond it, interest outside an ISA becomes taxable. |
| First taxable portfolio | CGT annual exempt amount £3,000; dividend allowance £500 | Outside wrappers, gains above £3,000 a year are taxable (18% / 24% on shares), and at a 3.5% illustrative yield about £14,300 of shares fills the dividend allowance. This is why the £20,000 ISA allowance does the heavy lifting first. |
| £100,000 income | Personal allowance tapers: £1 lost per £2 above £100,000 | Between £100,000 and £125,140 the effective marginal rate reaches roughly 60%. A milestone that arrives as a pay rise and behaves like a cliff. |
| £325,000 estate | IHT nil-rate band, frozen to 2031 | The first £ of estate above the band (after any residence band and spouse transfers) faces 40%. From April 2027 unused pensions count too; see What changed. |
| £1,000,000 (couple) | Two nil-rate bands + two residence bands | The theoretical maximum a couple passes IHT-free with a home left to direct descendants: £325,000 × 2 plus £175,000 × 2. Above it, planning stops being optional paperwork. |
Read down the ladder and a pattern appears: the early rungs are about allowances (keeping growth untaxed), the middle rung is an income-tax cliff, and the top rungs are estate questions. Net worth does not just grow; the kind of problem it poses changes as it grows, which is why a milestone list beats a single number.
Information and guidance only. Not personal advice. Growth and interest rates here are illustrative; investment values can fall as well as rise. Figures from rules bundle UK-2026.1.1 (2026/27): PSA £1,000 / £500, CGT exempt amount £3,000, dividend allowance £500, ISA allowance £20,000, personal allowance taper £100,000 to £125,140, nil-rate band £325,000, residence band £175,000, couple maximum £1,000,000. Ladder arithmetic machine-checked (£1,000 ÷ 4.5% ≈ £22,200; £500 ÷ 3.5% ≈ £14,300; milestone years simulated). Published 7 August 2026 · figures last verified 7 August 2026.
Sonuswealth is pre-launch. The app shows which rung your household is on and which threshold is next, with the rule behind it in plain English.