5. June 2026
Still on .NET 8 or 9? You've Got the Same Deadline Either Way. .NET 10 and .NET 11 (Preview) Are Here.
Microsoft ships a new major .NET version every November, alternating between Long Term Support (LTS) releases and Standard Term Support (STS) releases. .NET 10, which arrived in November 2025, is an LTS release and the current version everyone should be targeting.
The temptation for many businesses is to wait things out and skip a version along the way or to leave it alone because everything is working fine. Reasonable in theory, but what tends to happen in practice is that a version gets skipped with good intentions of catching up on the next one, then the next one arrives before anyone has made a decision, and before long your software is two or three versions behind with an ever-growing list of reasons why now still isn't quite the right time to deal with it.
Whether you're on .NET 8 or .NET 9, your end-of-support date is the same, November 2026. Microsoft recently extended STS support from 18 to 24 months, meaning both versions now expire simultaneously. Played it safe with .NET 8 LTS, or jumped ahead to .NET 9 for the newer features? Either way, the clock reads the same. Or still sat on something older?
The upgrade target for both is .NET 10, supported until November 2028.
What does .NET 10 actually bring to the table?
Beyond the version number, .NET 10 continues the performance trajectory that has made modern .NET a genuinely strong runtime to build on. Faster startup times, a lower memory footprint, and runtime efficiencies that compound over time are particularly noticeable for APIs and background services running in Azure. On the language side, C# refinements in recent versions have steadily reduced boilerplate and made codebases easier to read and maintain, which quietly lowers the cost of every piece of development work you commission going forward.
For businesses running workloads in Azure, .NET 10 also integrates more cleanly with containerisation, Azure Functions, and the broader Microsoft ecosystem which drives smaller infrastructure bills and more straightforward deployment pipelines over time.
Why it matters?
Custom software is an investment rather than a one-off build, and the reason most businesses go bespoke in the first place is that off-the-shelf products couldn't quite do what was needed. That investment doesn't expire, but it does depreciate if it isn't maintained. Treat your custom development like your product, maintain it, evolve it and change it over time to drive value. Keeping your .NET version current is probably the most cost-effective thing you can do to extend the useful life of what you've already built, not because upgrading is trivial, but because not upgrading compounds into something far more expensive over time. Technical debt is real, and it charges interest.
A business that upgrades incrementally, moving from .NET 8 or 9 to .NET 10 as a planned step, typically spends a fraction of what it costs to modernise software that has been left to drift for five years or more. We've seen both scenarios up close and know which drives the best outcomes.
What to do right now?
If you're on .NET 8 or .NET 9, you have until November 2026 to migrate to .NET 10, and the time to plan that move is now rather than when the end-of-support notice lands. The runway is shorter than it looks, particularly if your software has grown in complexity or your development team has limited capacity. If you're on .NET 6 or earlier, this has moved from something worth thinking about to something you need to act on.
Custom development doesn’t have to be anxiety inducing, or something to panic about, but you do need a plan, and the earlier that plan exists the less it tends to cost.
Contact us on hello@deltatechnology.co.uk for a conversation around your custom developed solutions. We are experts in this field and can offer solid advice on what your business should do next.