Passive income investing mistakes are more common than most retail portfolios reveal, and three in particular keep destroying value that dividends alone cannot restore.
Three Passive Income Investing Mistakes and Why They Recur
The first is fixating on the highest yield available. A double-digit payout looks compelling until the cash flow behind it gives way. Vodafone is the textbook example: it halved its dividend in 2025, punching a hole in Vodafone shareholders’ passive income at the time.
The converse error is assuming every elevated yield is a warning sign. Greencoat UK Wind (UKW) carries a yield of around 10% and trades at a 16.0% discount to net asset value (estimated, as at 30 June 2025), according to its Greencoat UK Wind half-year report. Weaker asset values are a genuine risk for the trust. Even so, it has raised its dividend ahead of inflation for 12 consecutive years.
The dividend picture carries one important update. Greencoat recently switched from RPI to CPI indexation, following the UK government’s decision to apply CPI to incentive payments under the Renewables Obligation Certificate scheme, according to the Association of Investment Companies. The revised 2025 dividend target stands at 10.7 pence per share, in line with the 3.4% CPI rate recorded in December 2024. Greencoat’s FY2024 final results show total dividends of 10 pence per share for the year ended 31 December 2024, supported by net cash generation of £278.7 million.
The policy change does not break the progressive record; it resets the index used to calculate annual increases. Investors should verify which version of the yield figure they are working from, since the AIC article cited an implied yield of approximately 10.9% at an earlier share price of 98p, while Greencoat’s own half-year report places the share price at 120.5 pence as at 30 June 2025, with a NAV per share of 143.4 pence (estimated, Alternative Performance Measure) and total shareholder return for that period of 11.5% (estimated, Alternative Performance Measure).
BT Group and the Total Return Test
The second passive income investing mistake is buying a dividend stock without examining what the share price has done over the same period. BT Group (BT.A) illustrates the point.
BT carries a forecast yield of around 4.1% for the current year. At its FY26 results in May, the company restated its plan ‘to grow the dividend by low to mid single digit percent per annum in FY27 and onwards’. Its BT Group FY26 full-year results show a declared dividend of 8.32 pence per share, with full-year revenue of £19.7 billion (down 3%) and adjusted EBITDA of £8.2 billion, flat year on year. Reported profit before tax rose 8% to £1.4 billion.
The free cash flow trajectory supports the commitment. BT projects normalised free cash flow of approximately £2.0 billion in FY27, rising to approximately £3.0 billion by the end of the decade. Its transformation savings target was raised to £3.7 billion (from £3.0 billion), though the programme was extended by one year to FY30 and the cost to achieve it increased to £1.4 billion from £1.0 billion.
The problem sits alongside those numbers: BT.A has fallen 53% over the past 10 years. The income was real. The capital erosion was real too. Dividend income and share price performance are not separate questions; they are two components of total return, and passive income portfolios that track only one of them will systematically undercount what they are actually earning or losing.
Sector Concentration: The Third Risk
The third passive income investing mistake is building a portfolio that looks diversified by name but sits almost entirely within one or two sectors. It happens naturally. Certain sectors dominate dividend screens at any given time, and investors gravitate toward businesses they understand best. The result is exposure to a single regulatory cycle, commodity price, or interest rate move.
Screening for genuinely progressive, cash-covered dividends is the right starting point. Adding a total return filter removes businesses that pay dividends by depleting capital value. Spreading the result across sectors is the final check, and it is the one most portfolios skip.
For BT specifically, the question over the coming years is whether the free cash flow ramp to approximately £3.0 billion by end of decade materialises on schedule. That figure will determine whether the dividend growth commitment holds and whether the share price can recover any of the ground lost over the past decade.
