Property: the 60-day rule

Selling a UK residential property that isn't your main home — a buy-to-let, an inherited property, or a second home — triggers a strict requirement to report the gain and pay the estimated CGT within 60 days of completion, using HMRC's dedicated online property CGT service. This is far faster than the normal Self-Assessment deadline and easy to overlook if you're not expecting it.

What can reduce a property gain

  • Costs of buying and selling — legal fees, estate agent fees, Stamp Duty paid on purchase
  • Costs of significant improvements (not routine maintenance or repairs)
  • Private Residence Relief for any period the property was genuinely your main home
  • Lettings relief, in narrower circumstances than it used to apply — check current eligibility rather than assuming

Shares: a different reporting timetable

Gains on shares held outside an ISA are reported through your normal annual Self-Assessment return, not the 60-day property route — giving considerably more time to calculate and report accurately, provided the gain (or total sale proceeds) exceeds the reporting thresholds.

Matching rules for shares

If you've bought the same company's shares on different occasions at different prices, specific "matching rules" determine which shares are treated as sold first for CGT purposes (broadly: same-day purchases, then purchases within the following 30 days, then a pooled average cost for everything else) — this affects the calculated gain and can be a common source of errors.

Keeping records

For both property and shares, keep purchase and sale records, including dates, prices, and associated costs, for at least the period HMRC can enquire into your return — losing track of original purchase costs (particularly for property bought decades ago, or shares acquired through inheritance) makes an accurate calculation much harder.

Key takeaways

  • Non-main-home property sales must be reported and paid within 60 days — much faster than shares.
  • Share gains go through your normal annual Self-Assessment return instead.
  • Specific share-matching rules determine which shares are treated as sold for tax purposes.
  • Keep detailed purchase and cost records for both, ideally as you go rather than reconstructing later.