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TikTok ad captions can't contain links, @ or hashtags

TikTok states the caption supports none of them. Copy built around a hashtag or an @mention arrives broken, and the spec page states no character count.

TikTok's in-feed specification states the ad caption is "displayed in white with a uniform font that can't be customized" and "does not support any clickable links, symbols (@), or hashtags".

That rules out a lot of copy patterns people bring from organic. A caption built around a branded hashtag, or one that @mentions a creator, doesn't degrade gracefully. It just reads as broken.

There's no published character count

Worth stating plainly, because everyone else publishes one: TikTok's own in-feed specification page states no character limit for ad text. We checked it twice. The 100-character figure that appears in most guides doesn't appear in TikTok's documentation, so we don't assert it either.

Write the caption short because it sits over video and truncates behind a "See more", not because a specific number has been published.

Spark Ads take the caption from the post

A Spark Ad promotes an organic post that already exists, and TikTok states its captions are "extracted directly from the organic video captions", with a maximum of four lines displayed. So the copy decision happens when the post is written, not in Ads Manager. Choosing Spark after writing ad copy means throwing that copy away, which is why that decision belongs near the top of a TikTok build.

See the TikTok ad specs, quoted with sources.