Tiberius & Philip

Tiberius reigned 18 September 14 AD – 16 March 37 AD (22 years) - Click

About this time it was that Philip, Herod's ' brother, departed this life, in the twentieth year* of the reign of Tiberius, after he had been tetrarch of Trachonitis and Gaulanitis, and of the nation of the Bataneans also, thirty-seven years.
Josephus, Antiquities 18.106.

*= Manuscripts from 1544AD or older all have twenty-two.

Philip died in the 22nd year of Tiberius after ruling for 37 years.

37AD - 37 = 1BC (no year zero)

Philip started his reign shortly after Herod died. So if Philip started in 1BC then Herod must have died shortly before that.

The widely accepted date for Herod’s death was 4BC for a long time. But even Wikipedia starts to catch up because it lists 37– c. 4 BCE/ 1 CE - click

That allows for Jesus to be born as late as 1 BC.

Luke 3:1 Now in the fifteenth year of the reign of Tiberius Caesar, Pontius Pilate being governor of Judaea, and Herod being tetrarch of Galilee, and his brother Philip tetrarch of Ituraea and of the region of Trachonitis, and Lysanias the tetrarch of Abilene,

14 AD + 14 year* = 28 AD

*=14 AD is the first year.

Luke 3:23 And Jesus himself began to be about thirty years of age, being (as was supposed) the son of Joseph, which was the son of Heli,

28 AD - 30 = 3BC (no year zero)

Jesus was baptized on Atonement Day 5 days before His birthday on the first day of Tabernacles

Conclusion #1: Philip started his reign on 1 BC.

Conclusion #2: Herod died in or shortly before 1 BC.

Conclusion #3: Jesus was born in 1 BC or earlier.

Conclusion #4: Jesus was born in 3 BC.