Muni bonds are the best way to go for that. You can still nail 4% plus after inflation and taxes there. You're not going to get risk-free anywhere, there's no such thing.
Sure - so you're factoring capital appreciation in to the total return for your 4% after tax number? Which would imply that you're not holding these to maturity though right?
[0]: https://index.barcap.com/Benchmark_Indices/Aggregate/Bond_In...