# Choosing Between .NET 6, .NET 8, and .NET 10 in 2026: A Practical Decision Guide

Every few months I get some version of this question from a client or a developer I'm mentoring: "we're still on .NET 6/8, should we upgrade, and to what?" It's rarely a simple yes or no, but as of right now, the calendar has made the answer unusually clear-cut. Here's how I actually walk through this decision.

### Start with where you actually are, not where you want to be

Before talking features, the support calendar has to drive the conversation, because a feature comparison doesn't matter if the runtime underneath it stops receiving security patches.

**.NET 6**: end of support was November 12, 2024. If production workloads are still on it, that's not a looming risk, it's an existing one. Every day since that date has been a day without security patches for anything discovered afterward.

**.NET 8**: current LTS, but its support window closes November 10, 2026. As I'm writing this, that's a matter of weeks away, not a comfortable planning horizon.

**.NET 9**: an STS release, and its extended support window happens to land on the exact same date as .NET 8's, November 10, 2026, because Microsoft's STS support extension from 18 to 24 months lined the math up that way.

**.NET 10**: current LTS, released November 11, 2025, supported through November 14, 2028. This is where the runway actually is.

### The decision tree I actually use

**Are you starting something new?**  
Target .NET 10. There's no scenario where starting a greenfield project on a version with weeks of remaining support, or one already unsupported, makes sense over the version with three years of runway.

**Are you on .NET 8 or .NET 9?**  
This is a "this quarter" migration, not a "next year" one. The good news: moving between adjacent LTS versions is typically a retarget-and-recompile exercise, updating the target framework, resolving whatever the compiler flags as a breaking change, and re-testing. It's rarely a rewrite. The bad news: with .NET 8 and .NET 9 both expiring the same day, migration support and consulting capacity around that date is going to get crowded. Moving earlier, not at the deadline, is the difference between a calm migration and a scramble.

**Are you on .NET 6?**  
Treat this as urgent. Two years of unpatched runtime in production is a real exposure that's already been sitting there, not a hypothetical one you're choosing to accept going forward. If nothing else on your roadmap is genuinely more urgent than closing a two-year-old security gap, this should be first.

### What actually changed, if the version jump matters to your decision

Between .NET 6 and .NET 8: Native AOT matured into something production-viable, giving real startup time and memory footprint improvements, particularly valuable for containerized workloads. Minimal APIs gained real tooling support. JIT and garbage collector improvements delivered measurable throughput gains.

Between .NET 8 and .NET 10: this is the bigger jump. Built-in AI integration through the Microsoft Agent Framework, meaning AI features no longer require stitching together third-party SDKs from scratch. EF Core 10 added native vector search tied to SQL Server 2025, directly relevant if you're building retrieval-augmented AI features. C# 14 introduced field-backed properties, closing a real gap between simple auto-properties and ones needing custom logic. Post-quantum cryptography support expanded meaningfully, worth tracking if you're in fintech or handling long-lived sensitive data.

### Where migrations actually lose time

The framework upgrade itself is rarely what costs weeks. What costs weeks is what the upgrade surfaces: a dependency nobody's touched in two years, a workaround for a bug that's since been fixed a different way upstream, code that quietly relied on behavior that's changed. I budget time for discovery, not just for the mechanical retarget, because the mechanical part is almost never where the real cost hides.

### The bottom line

Given where the calendar sits right now, .NET 10 isn't just the newest option, it's the only one with a genuinely comfortable runway. If you're on .NET 8 or .NET 9, the clock is real and close. If you're on .NET 6, the exposure isn't coming, it's already here. This is a good moment to stop treating the question as open and just make the call.