diff --git a/redbot/cogs/mod/kickban.py b/redbot/cogs/mod/kickban.py
index 600461e9101..570e477c41b 100644
--- a/redbot/cogs/mod/kickban.py
+++ b/redbot/cogs/mod/kickban.py
@@ -16,6 +16,7 @@
     format_perms_list,
 )
 from redbot.core.utils.mod import get_audit_reason
+from redbot.core.utils.predicates import MessagePredicate
 from .abc import MixinMeta
 from .utils import is_allowed_by_hierarchy
 
@@ -575,7 +576,7 @@ def remove_processed(ids):
     async def tempban(
         self,
         ctx: commands.Context,
-        member: discord.Member,
+        member: Union[discord.Member, RawUserIdConverter],
         duration: Optional[commands.TimedeltaConverter] = None,
         days: Optional[int] = None,
         *,
@@ -596,24 +597,30 @@ async def tempban(
         """
         guild = ctx.guild
         author = ctx.author
+        in_server = True
+
+        if isinstance(member, int):
+            in_server = False
+            member = self.bot.get_user(member) or discord.Object(id=member)
 
         if author == member:
             await ctx.send(
                 _("I cannot let you do that. Self-harm is bad {}").format("\N{PENSIVE FACE}")
             )
             return
-        elif not await is_allowed_by_hierarchy(self.bot, self.config, guild, author, member):
-            await ctx.send(
-                _(
-                    "I cannot let you do that. You are "
-                    "not higher than the user in the role "
-                    "hierarchy."
+        elif in_server:
+            if not await is_allowed_by_hierarchy(self.bot, self.config, guild, author, member):
+                await ctx.send(
+                    (
+                        "I cannot let you do that. You are "
+                        "not higher than the user in the role "
+                        "hierarchy."
+                    )
                 )
-            )
-            return
-        elif guild.me.top_role <= member.top_role or member == guild.owner:
-            await ctx.send(_("I cannot do that due to Discord hierarchy rules."))
-            return
+                return
+            elif guild.me.top_role <= member.top_role or member == guild.owner:
+                await ctx.send(_("I cannot do that due to Discord hierarchy rules."))
+                return
 
         guild_data = await self.config.guild(guild).all()
 
@@ -629,9 +636,64 @@ async def tempban(
             return
         invite = await self.get_invite_for_reinvite(ctx, int(duration.total_seconds() + 86400))
 
-        await self.config.member(member).banned_until.set(unban_time.timestamp())
+        # Check if user is already banned/tempbanned and prompt for a downgrade
+        async def prompt_downgrade(banned_until):
+            if ctx.assume_yes:
+                return True
+
+            if banned_until:
+                prompt = await ctx.send(
+                    (
+                        f"User is already tempbanned expiring <t:{int(banned_until)}:R>, proceed?"
+                        f" (yes/no)"
+                    )
+                )
+            else:
+                prompt = await ctx.send(
+                    (f"This will downgrade the ban to a tempban, proceed?" f" (yes/no)")
+                )
+            response = await ctx.bot.wait_for("message", check=MessagePredicate.same_context(ctx))
+
+            if response.content.lower().startswith("y"):
+                with contextlib.suppress(discord.NotFound):
+                    await prompt.delete()
+                with contextlib.suppress(discord.HTTPException):
+                    await response.delete()
+                    return True
+            else:
+                await ctx.send("Cancelled.")
+                return False
+
+            if response.content.lower().startswith("y"):
+                with contextlib.suppress(discord.NotFound):
+                    await prompt.delete()
+                with contextlib.suppress(discord.HTTPException):
+                    await response.delete()
+                return True
+            else:
+                await ctx.send("Cancelled.")
+                return False
+
+        try:
+            await guild.fetch_ban(member)
+        except discord.NotFound:
+            pass
+        else:
+            async with self.config.guild(guild).current_tempbans() as current_tempbans:
+                banned_until = False
+                if member.id in current_tempbans:
+                    banned_until = await self.config.member_from_ids(
+                        guild.id, member.id
+                    ).banned_until()
+            if not await prompt_downgrade(banned_until):
+                return
+
+        await self.config.member_from_ids(guild.id, member.id).banned_until.set(
+            unban_time.timestamp()
+        )
         async with self.config.guild(guild).current_tempbans() as current_tempbans:
-            current_tempbans.append(member.id)
+            if not member.id in current_tempbans:
+                current_tempbans.append(member.id)
 
         with contextlib.suppress(discord.HTTPException):
             # We don't want blocked DMs preventing us from banning
@@ -644,7 +706,8 @@ async def tempban(
                 msg += _("\n\nHere is an invite for when your ban expires: {invite_link}").format(
                     invite_link=invite
                 )
-            await member.send(msg)
+            if in_server:
+                await member.send(msg)
 
         audit_reason = get_audit_reason(author, reason, shorten=True)