A Stocks and Shares ISA stuffed with dividend shares is one of the more straightforward routes to passive income, but the maths sets a clear entry price. Reaching a monthly passive income of £1,000 requires either a large lump sum invested from day one or a patient decade of contributions and compounding.
Building to £240,000
The target income is £1,000 a month, or £12,000 a year. At a dividend yield of 5%, that arithmetic points to a Stocks and Shares ISA worth £240,000. The FTSE 100’s current average yield sits at roughly 3%, so hitting 5% requires picking selectively, though it is achievable without straying far from blue-chip territory.
Few investors have £240,000 sitting ready to deploy. The alternative is to build toward that figure: contribute £20,000 a year, reinvest all dividends, and compound at 5% annually. On those assumptions the ISA crosses £240,000 inside a decade.
The reinvestment phase is where compounding does its work. Each dividend buys additional shares; those shares generate their own dividends; and the cycle continues. Only once the target portfolio size is reached does the investor switch from reinvesting to drawing income.
The timeline and contribution level are not fixed. A higher annual contribution shortens the decade; a lower yield assumption extends it. The £1,000-a-month figure simply illustrates the relationship between portfolio size, yield, and income, and the same approach scales to any target.
M&G as a Dividend Candidate Inside a Stocks and Shares ISA
One FTSE 100 share that fits the dividend-focused approach is M&G (LSE: MNG), the asset manager. The snippet cited a 6% yield, but Yahoo Finance reported the yield at approximately 7% at the time of the company’s results, and that figure supersedes the earlier estimate.
On the dividend itself: M&G declared a second interim dividend of 13.8 pence per share for 2025, bringing the total 2025 dividend to 20.5 pence per share, according to the M&G 2025 Annual Report announcement on Investegate. Payment is scheduled for 30 April 2026, with an ex-dividend date of 19 March 2026.
M&G also offers shareholders a Dividend Reinvestment Plan (DRIP), allowing cash dividends to be used to purchase additional shares automatically, which suits investors in the compounding phase of the strategy described above.
The underlying business has improved materially. Full-year 2025 net inflows from open business swung to £7.8 billion, from outflows of £1.9 billion in 2024, Yahoo Finance reported. At the half-year stage, the London Stock Exchange announcement of M&G’s H1 2025 results showed Asset Management revenue of £514 million, up from £499 million in H1 2024, with the cost-to-income ratio improving to 75% from 77% and the Shareholder Solvency II coverage ratio at 230%.
On the dividend’s track record, Simply Wall St aggregator data shows M&G’s dividend has grown at an average of 9.5% per year over the past six years. The same source puts the trailing payout ratio at approximately 163%, which warrants attention: a payout ratio above 100% implies the company is covering its dividend from sources beyond reported earnings, which may not be sustainable indefinitely.
The risk the snippet identified has not disappeared entirely. M&G has historically struggled when volatile markets prompt policyholders to withdraw funds. The 2025 inflow reversal is an improvement, but investors would be prudent to monitor net flow figures each reporting period as a check on whether the recovery is holding.
Stock-picking matters here. A 5% or 7% yield only contributes to the passive income target if the dividend is maintained. Understanding a company’s free cash flow, payout ratio, and client-flow dynamics before buying is part of the discipline that separates sustainable income from a yield trap.
M&G’s next scheduled dividend payment on 30 April 2026 will be a concrete test of whether the improved net-flow momentum reported for 2025 has given management sufficient confidence to sustain the payout trajectory.
