There are two verb tense options when writing fiction: past and present. And each has its own challenges.
Writing in the past tense
Most fiction is written in the past tense, which means that the present time of the story's action is conveyed using simple past. Depending on the writer's approach, this can either give the sense that the story is being told at a later date or that it's unfolding in the present moment.
The four main tenses used in a past tense narrative
For story's present:
simple past: Emily stared at the ocean. I stared at Emily.
continuous past: Emily was staring at the ocean. I was staring at Emily.
For the story's past:
past perfect: Yesterday, Emily had stared at the ocean for the entire day.
past perfect continuous: Emily had been staring at the ocean for hours. I had been staring at Emily the entire time.
Common mistakes when writing in the past tense
The modals will, may, and can
In a story written in the past tense, the present tense modal verbs will, can, and may should only show up in dialogue or direct thoughts. Instead, use the past tense would, could, and might in a past tense narrative.
These examples of modals in the present tense are from The Hunger Games by Suzanne Collins:
The reaping isn't until two. May as well sleep in.
Entrails. No hissing. This is the closest we will ever come to love.
If The Hunger Games had been written in the past tense, these examples would look like this instead:
The reaping wasn't until two. Might as well sleep in.
Entrails. No hissing. This was the closest we would ever come to love.
The converse is not true. Even though they're past tense modals, would, might, and could do show up in present tense narrative (and in dialogue and direct thoughts in a past tense narrative) in the conditional mood.
Again, examples are from The Hunger Games.
Even though trespassing in the woods is illegal ... more people would risk it they had weapons.
I watch as Gale pulls out his knife and slices the bread. He could be my brother.
And don't slide over would, could, and might when self-editing your past tense narrative, either. When the conditional mood is used in the past tense, you often need to use past tense modals.
In a past tense narrative, the previous examples would look like this:
Even though trespassing in the woods was illegal ... more people would have risked it if they had weapons.
I watched as Gale pulled out his knife and sliced the bread. He could have been my brother.
In conjunctions, 's can either stand for is or has, which are present tense verbs, but never was. It's fairly common for me to see it's as a conjunction for it was in the narrative in past tense manuscripts, and this is an easy mistake to overlook when self-editing.
Accidentally switching to present tense after dialogue or direct thoughts
Accidentally switching to present tense isn't that common in third person past manuscripts, but if it's going to happen, it's usually after dialogue or direct thoughts that are in present tense; it's easy to continue in the tense of the dialogue or thought even after it has ended.
In first person past manuscripts, accidental switches to present tense are more common. Probably because the main character is also the narrator, so the line between direct thoughts and narrative can get confused.
Also, a first-person narrator who is relating the story after the fact in past tense can use the present tense to offer commentary or speak of things that are still true after the time of the story. This is not accidental tense switching but, like all shifts in narrative distance, can confuse the reader if not handled skillfully.
Writing in the present tense
The present tense has become more popular in modern times, probably due to the immediacy of movies and television and the influence of scripts and screenplays. It's especially popular in young adult fiction, literary fiction, and romance. The present time of the story is conveyed using the present tense.
The four main tenses you'll use in present tense narrative
For the story's present:
simple present: Emily stares at the ocean. I stare at Emily.
present continuous: Emily is staring at the ocean. I am staring at Emily.
For the story's past:
simple past: Yesterday, Emily stared at the ocean for the entire day.
past continuous: I remember that Emily was staring at the ocean for hours. I was staring at Emily the entire time.
Past perfect in a present tense narrative:
Past perfect shows up only rarely in a present tense story, when the narrator is flashing back to a previous event and needs to reference something that happened even earlier than that event.
past perfect: Emily can only stare at the ocean for an hour today (present). Yesterday, she stared at the ocean for a full ten hours (past), but if she had known the ocean would be so compelling, she would have packed a lunch (past perfect).
What to watch out for in present tense
Tense switching errors are much more common in present tense manuscripts, so if you're writing in present tense, you should do a separate editing pass just to check tense consistency.
But don't mistake using appropriate verb tenses for tense switching. The verb tense used for the story's present must be consistent, but other tenses are needed to show past or future events. Only shift tenses if there's an intentional time change.
Using said as a dialogue tag can be automatic, so it frequently pops up in present tense manuscripts, despite being the past tense of say and says.
Dialogue tags can feel an awful lot like telling in a present tense narrative—which can take away from the immediacy—and they don't always disappear as easily as in past tense stories. Instead, try using action beats and narrative when you need to clarify who's speaking. This can help keep a present tense story feeling in-the-moment.
In present-tense manuscripts and self-published novels, it's not uncommon to see flashbacks in past perfect when they should be in simple past. Remember to flash back one step at a time: present → simple past → past perfect.
Mary loves (present) being the principal, but she hated (past) being a teacher. She once said (past) she didn't know how she had survived (past perfect) ten years teaching kindergarten.
Telling the future
The benefit of writing in present tense is the sense of immediacy it imparts, making the story feel like it's unfolding in the now. When the narrator appears to have awareness of future events, it disrupts this sense and can trip up the reader.
A narrator of a past tense story can often get away with saying something like "little did I know that my whole world was about to change," without sounding clairvoyant, but a narrator who is describing events as they happen in the present, can't. At least not without jarring the reader.
Getting verb tenses right can sometimes be tricky, but the more you get right in your manuscript before submitting to editors, the less work they'll have to do on mechanical issues and the more time they can spend on making your writing shine. And you might even save money.
For more on how to save money on editing, check out Nine Ways to Save Money on Editing.