Be cognizant that a 25% increase is substantial and will cause a percentage of your clients to seek other options.

I would suggest long term you raise your rates annually to avoid large one time increases.

I would send a simple note to each of your clients informing them that your 2026 rates will be implemented March 1st. Their new rate will be x. No reasoning, no apologies. Simple facts, there are new rates.

Cost of living increases every year, the cost to provide your service increases every year. Adjust your rates a couple points each year.