If you have expertise in a skill, is only your initial proficiency bonus doubled, or does it scale as you level up? [duplicate]

I understand that having expertise in a a skill doubles your proficiency in it, but is it just the initial proficiency that's doubled or does it include proficiency you gain from leveling up?

e.g. If I had +2 persuasion and expertise in it it would be +4. If I then level up would it now be +6 or +8?

• Why would it go to +8? Unless you leveled from 4th level to 9th level...? Nov 17, 2018 at 1:53
• I'm voting this as unclear because it seems there is some misunderstanding in how skill bonus and proficiencies work, but I can't figure out what misunderstanding this is. When the asker provides more detail on why he thinks it should be +8, we can actually answer it Nov 17, 2018 at 1:55
• Nov 17, 2018 at 1:55
• @KorvinStarmast The question is not clear at all, because the numbers don't match his question. It also does not seem like a dupe to the linked question, as that asks if the modifier bonus from the attribute (e.g. Charisma) doubles up while this one asks what happens if you level up and the bonus from proficiency changes. Nov 17, 2018 at 4:16
• From the way it's worded, he had +2 proficiency, which was doubled to +4. If he then gains +1 bonus proficiency getting level 5 (going to +3), his doubt should be between +5 (+2*2 + 1) or +6 (+3*2). I have no idea how he got to +8, and the answers trying to address it clearly also don't. Nov 17, 2018 at 4:18

Double your current proficiency bonus

The expertise feature says the following (emphasis mine)

At 1st level, choose two of your skill proficiencies, or one of your skill proficiencies and your proficiency with Thieves' Tools. Your proficiency bonus is doubled for any ability check you make that uses either of the chosen proficiencies.

The text says your proficiency bonus is doubled for these skills. If does not say that you get your initial proficiency bonus as a bonus.

In other words if your proficiency bonus is +2 (total +4) your expertise skills get an extra +2, if your proficiency bonus is +3 those skills get an extra plus +3 (total +6).

Whatever your proficiency bonus is at your current level, Expertise doubles that.

If you go from proficiency +2 to +3, Expertise means the net bonus goes from +4 to +6 (plus whatever your stat mod adds).

• The asker does mention he is originally at a level where his proficiency bonus is +2, not +3. So it's quite unclear how he is going from +2 to +4. Nov 17, 2018 at 1:57