Question: “Is it ever okay to switch tenses in a story?”
Answer: Since you included the word ever, the answer is yes. Sometimes switching up your tenses adds power and interest. But generally no. These tips should take the tension out of working with tense and help you decide.
#1 – In general, choose one and stick to either present or past.
Because we may switch back and forth naturally in conversation, tense changes can slip easily into writing. It may take a keen eye to notice it, but some people will. Pointless switches signal lax editing and may be confusing. Only switch when you have a clear reason.
Present tense can enhance the tension and make short stories with lots of drama even more compelling to read. It’s an especially good choice for stories written to stand on their own. Past tense may feel more natural and works well for anthologies, composite stories, and memoir.
#2 – You may need to mix tenses if you are writing in the present about someone who died.
My father loved to tell stories about the olden days, and every now and then he e-mailed stories about cowboys, hunting jack rabbits, raising chickens and other nostalgic topics to family and friends. He was a masterful storyteller, and his work is polished and entertaining. Although it barely scratches the surface of his life, it’s a cherished legacy. We looked forward to each story.
He DID love, and his (remaining) work (still) IS . . . Mixing tenses is the only accurate way to state this and other cases where one thing is gone and a related one endures. This sort of shift is clear and easily understood.
#3 – Switching tense for flashbacks may be a powerful option and set them apart.
If your main story is written in the past tense and you reflect back to an especially dramatic scene, it can work well to write that scene in present tense, bringing the reader into the moment. Conversely, past tense makes sense for flashbacks inserted into stories written in present tense. Even if the reader does not specifically notice the shift in time, the change of tense signals it to the unconscious, preventing most confusion. Tips on writing successful flashbacks abound on line.
Think of tense as a two-lane highway with fast-moving traffic. In general it works best to stick with your lane. Look carefully for the right time and signal your intent when you have reason to change.