When can you do things that do not require an action?

Question

There are a number of things you can do that do not require an action. These include:

Concentration:

You can end concentration at any time (no action required).

Countercharm

The performance ends early if you are incapacitated or silenced or if you voluntarily end it (no action required).

Luck Blade

If the sword is on your person, you can call on its luck (no action required)

Conjure Animals

They obey any verbal commands that you issue to them (no action required by you).

Does this mean these "non-actions" can be performed at any time, even during someone else's turn or in the middle of dice roll resolution, etc?

(This question is a spin off of the question about when you can end concentration, answers tend to rely on a twitter post from Jeremy Crawford that just quotes the rules right back at the asker, which is interpreted by some to mean "yes, you can end concentration during other turns". This presents an immediate problem because Alter Self, for example, says "At any time for the duration of the spell, you can use your action to change your appearance in this way again." V2Blast then asserted that the key wording wasn't "any time" it was "no action", and that anything that didn't require an action can be activated when you cannot take actions. Can this argument be generalized or is it a very special case interpretation of one particular mechanic to attempt to make it make sense?)

Note: This answer is not only about Concentration. In other threads people have argued that since Concentration says "at any time" you can do it in other turns. However the other examples don't use this language. Particularly Conjure Animals specifically says "verbal command" which would normally be possible only on your turn, and does not say "at any time". Please address more than just Concentration in your answer.

Answer 1

If you're taking turns, all these things must be done on your turn.

The rules define several categories of activity that can take place on your turn:

On your turn, you can move a distance up to your speed and take one action. ...

Various class features, spells, and other abilities let you take an additional action on your turn called a bonus action.... You can take a bonus action only when a special ability, spell, or other feature of the game states that you can do something as a bonus action.

And the one that's important here:

Your turn can include a variety of flourishes that require neither your action nor your move.

This is followed by the only case where the rules permit you to act when it's not your turn:

Certain special abilities, spells, and situations allow you to take a special action called a reaction. A reaction is an instant response to a trigger of some kind, which can occur on your turn or on someone else's....

When you take a reaction, you can't take another one until the start of your next turn. If the reaction interrupts another creature's turn, that creature can continue its turn right after the reaction.

So:

• Reactions explicitly can be done outside your turn, and there's a rule explaining what happens when you interrupt another creature's turn with a reaction.

• All other forms of activity explicitly must be done during your turn. This includes movement, actions, bonus actions, and an "other activity" category of things that require neither movement nor an action.

• Bonus actions have language limiting them to class features, spells, and other mechanics that specify that they use a bonus action. Same with reactions. Actions and "other activity" have no such limitation and are open-ended.

• Ending concentration, dropping Countercharm, etc. are activities that require neither movement nor an action. Therefore they are "other activity" and must be done on your turn.

"At any time" does not override the normal timing rules.

This is most obvious with something like the alter self spell, which allows you to change appearance "at any time" by using an action. "You can use your action" means it's subject to the timing rules for actions--you can't do it outside your turn, or on a turn when you've already used your action, or while surprised.

Non-actions like talking or dropping concentration also have timing rules, as described above. They're not the same as for actions (in particular, interacting with an object must be done during your action or your move) but they exist.

Answer 2

They can be done at anytime during Step 2 of the rules on p.5 of the PHB

1. The DM describes the environment
2. The players describe what they want to do
3. The DM narrates the result of the character's actions

So, anytime the DM is not “describing the environment“ nor “narrating the result of the character's actions” the player can describe what they want to do.

This can be outside of the player’s turn but not between the DM saying “the goblin attacks” and the results of that attack happening because that’s all part of step 1. Nor can it be between the player saying “I pick the lock” and the trap going off because that’s part of step 3.

Answer 3

There are no secret rules

Does this mean these "non-actions" can be performed at any time

No. The rules do only what they say they do. The general rule is you spend your Action on your turn to do something. Some things expend your Bonus Action or Reaction — in these cases, their descriptions say that explicitly. By the way, your reaction can be expended during your own turn too.

In the described case "no action required" only means you don't spend any kind of action. Normally, as a player, in combat you do things on your turn, unless a more specific rule (and the DM) states otherwise.

The examples provided have their own respective timings

Concentration — can be ended "at any time", presumably you can do this on other's person turn as well, see Can you end concentration on a spell during someone else's turn?

Countercharm — ends when "you voluntarily end it", for the precise timing (like "can I do that right after he releases an arrow but before it hits") ask your DM.

Luck Blade — can be used when you make an attack roll, ability check, or saving throw you dislike, but before this roll was resolved (the DM declared its narrative consequences). It's the only feature that can (and has to) be done in the middle of dice roll resolution.

Conjure Animals — you can command the spirits when you communicate with them ("issue a verbal command"), its timings depends on the table rules, see Can I say something to an ally when it's not my turn and we are both in combat?