Dividend calculator — methodology

Step one: what the holding is, whichever way you describe it

Two inputs, two ways of writing them down, and nothing downstream knows which was used:

from shares:  value = shares × share price      income = shares × dividend per share
from an amount: value = amount invested       income = amount × yield

The share figures are in pence, because UK equities are quoted in pence. That is not only convention: a dividend per share of 7.7p entered as £0.077 would be rounded to the nearest penny and become £0.08, a 4% error on the one figure the whole page multiplies up.

The yield shown in the breakdown is derived from those two numbers on both bases — it is a check on what you entered rather than an input in its own right.

Step two: the payment schedule, and reinvestment

The holding is treated as one unit at the start. multiple is how many of that unit are held; it begins at 1 and reinvestment is the only thing that moves it. For payment p of n a year, in year y:

unit price  = starting value × (1 + price growth)^(p/n)
payment     = multiple × starting annual dividend × (1 + dividend growth)^y ÷ n
value       = multiple × unit price
if reinvesting:  multiple ← multiple + payment ÷ unit price

Both growth terms are computed from the starting figures rather than by compounding last period’s already-rounded number, so twenty years of rounding cannot drift away from the rate you typed.

Two conventions in there are choices rather than facts. The price moves every period and the dividend steps once a year, because a share price moves continuously and a dividend is declared — a company paying quarterly does not raise its payment by a quarter of the annual growth each quarter, it pays the same amount four times and then a larger amount four times. And the periodic price factor is (1 + g)^(1/n), an effective conversion, so n of them compound to exactly the annual rate you typed; dividing by n instead would quietly turn 5% into about 5.09%.

The consequence, which the table is built to let you check: because a payment is a whole number of pence, closing value = value before the payment + the part reinvested holds exactly on every row, not approximately.

Step three: the tax, one year at a time

No rate is written into this calculator. Each year’s tax is the tax engine run twice and subtracted:

tax(y) = income tax(your other income + dividends in year y)
       − income tax(your other income)

Running it per year rather than once at a blended rate is what makes the £500 dividend allowance an annual nil-rate band. A single rate applied to a whole term would either use the allowance once or use it every year without saying so, and both are wrong by more than a rounding.

It also means the dividends meet whatever rate the income underneath them leaves them at. Income is taxed in a statutory order — other income, then savings interest, then dividends — so dividends are the top slice and the rate they meet is a property of the taxpayer rather than of the dividend. The dividend tax calculator shows the whole stack band by band; this page shows the dividend bands and stops.

The personal allowance is not simply set against earnings. Income Tax Act 2007 s.25(2) permits it to be allocated across income types in whichever way produces the lowest bill, and the engine searches that allocation rather than assuming one — so part of it routinely lands on the dividends of someone with a higher-rate salary. The breakdown shows that part as its own row, because otherwise the band column would not add up to the dividend above it.

The tax is charged whether or not the dividend was reinvested. A reinvestment plan is a receipt followed by a purchase; the receipt is taxable income in the year it arises. The schedule reinvests the whole payment and assumes the bill is settled from other money, which is what a dividend reinvestment plan actually does — so a reader who would have to sell part of the holding to pay it ends up with less than the closing values shown.

Rates and allowances

Dividend rates are UK-wide and are not devolved. Scottish rates apply to your other income only — but that other income still decides which dividend band the dividends fall in, which is the part most often got wrong.

Sources

• gov.uk — Tax on dividendsThe dividend allowance, the three dividend rates, and that dividends are treated as the top slice of income.
• gov.uk — Income tax rates and allowances: current and pastThe personal allowance and its taper, and the band thresholds the dividends are stacked against.
• gov.scot — Scottish income tax rates and bandsScottish rates apply to your other income, never to the dividends — but that other income still decides which dividend band the dividends meet.
• gov.uk — Individual Savings Accounts (ISAs)That dividends on shares held inside an ISA are not taxable, which is the one mechanism that removes the charge modelled here.

Six things this calculator does not do

• It does not forecast a dividend. The growth rates are yours. A company can cut, suspend or cancel a dividend at any time and many have; a high yield is very often the market’s judgement that a cut is coming, and no arithmetic can tell the difference.
• It applies 2026/27 rates to every year of the term. The dividend allowance and the dividend rates have both been changed repeatedly over the last decade and nothing here projects that forward. This is the largest assumption on the page.
• It does not model capital gains tax on the holding when you sell it, and reinvesting builds up exactly the kind of holding that produces one. The capital gains tax on shares calculator is where that belongs.
• It does not model an ISA or a pension wrapper. Dividends inside either are not taxable and none of the tax figures here apply to them. The stocks and shares ISA calculator prices the difference.
• It does not model pension contributions. Relief at source extends the basic-rate band, which is one of the main ways a higher-rate taxpayer reduces a dividend bill. computeTaxPosition does model it; this page has no input for it, so the tax shown is too high for anyone contributing. The pension tax relief calculator works out the band extension.
• It applies no withholding tax and no foreign dividend rules. The model is a UK dividend paid to a UK resident. Overseas dividends are commonly taxed at source, and offshore reporting funds, excess reportable income and equalisation payments have their own regime — none of it is here.