OP here...update for anyone who may be in the same boat. My company gave me a 25% salary increase.

You could use the federal government’s locality adjustment percentage to approximate what you should be paid by moving to the DMV.

https://www.federalpay.org/gs/locality

My company and my spouse's definitely give COL adjustments. They do it automatically when you update your address/information with HR. If yours doesn't then I would inquire with HR if it is possible to have an adjustment take place at the time of your move.

My company would give you zero. However, our annual raise takes into account zip code and we will consider that.

How is DC more expensive? I say that as I got a relo to DC and my salary and sign one package covered the cost difference. The move had no effect on my wife.

I would present it as you did in the OP. It doesn't hurt to ask but I'd also look for other job opportunities that pay more as well.

I’ll be moving to the DMV from a MCOL city within several months due to an incredible career opportunity for my partner.

I’m a well-respected member of a corporate environment and planning to transfer to one of my company’s offices in DMV. I want to ask for a market adjustment in pay since I am moving to a much higher COL area. I recognize it is my choice to move and not my company’s (so I shouldn’t expect anything) but also feel that I’d be missing an opportunity to ask if I don’t. And I don’t think it would be difficult for me to get a job at another company in the area and that’s something that should concern my current company if they’re thinking about not upping my salary. What I do is niche and I have a lot of good experience.

Does anyone else have this experience, or tips on how to ask? I know COVID has also skewed expectations around different salaries in different locations too, but again, missed opportunity not to ask.