We see this far too often with landlords.
Some don’t contribute to a pension at all, thinking rental income doesn’t qualify. Others over-contribute, assuming they will get tax relief and only discover the problem when HMRC raises an assessment.

Can landlords contribute to a pension tax-efficiently? Yes, but with limits. If your income is only from property, you can still contribute £3,600 gross per tax year (£2,880 paid in + £720 basic rate tax relief). This applies regardless of how high your rental profit is. Please note, the £3600 is not in addition to the £60,000 annual allowance. It sits within the £60,000 limit. So the maximum annual allowance is still £60,000 in total, not £63,600.

You can contribute to pension only from your “Relevant earnings”. So what count as this Relevant earnings? Salary / bonuses, Self-employment trading profits, Certain furnished holiday letting profits etc. are relevant earnings.

However income streams like Property rental income, Dividends, Interest, Capital gains, State pension etc. are not the relevant income streams for pension contribution.

Being said that here’s the twist most people miss:

Although property income doesn’t support pension contributions, it does count when testing whether your adjusted income exceeds £260,000 and if the tapered annual allowance applies.

Once tapering kicks in, the £60,000 allowance reduces by £1 for every £2 above £260,000 to a minimum of £10,000. Even if you have unused pension allowance brought forward, you cannot use rental income to fund it. Carry forward does not override the earnings rule.

If you’re a landlord, especially with multiple income streams, pension planning needs to be done carefully.