Long-term storage often results in rent increases, turning that initial rental fee into a fairly hefty bill. One way to get around this is to transfer your belongings to a smaller unit so you again pay those lower initial costs (though your rent will still eventually increase on the new unit, too). The disadvantage is that you end up with less space and more crowded boxes. Is the trade-off worth it?

How Much Longer Will You Have Things in Storage? 

First, how much longer will your items be in storage? If you are going to pull them out within a couple of months, transferring to another unit makes no sense. You'd still have to pay rent on your old unit (essentially double rent for a month) and possibly pay for a new lock. You may also have a new-unit fee, although some storage companies waive that fee if you're transferring between units in one day.

If you're going to have the unit for a few months more, however (so not one or two, but five, six, and so on), then it might make sense to switch to a smaller unit if you can get a good price. You won't have items in storage much longer, so accessing all the boxes isn't that much of a priority. If you can save money, you may benefit from crowding your items into a smaller unit.

If you're going to keep the unit for an indefinite time, though, then the decision gets a bit harder. You really don't want to cram everything into a small space for very long because, if you need to access a box that's in back, you have to pretty much take apart the storage unit. In that case, it may be better to keep the unit you have. If you can get a break on price by moving to another unit of the same size (because your lease on the new unit would start at a lower price), then that might be an option.

How Much Do You Actually Have?

Next, how much stuff do you actually have in storage? If you can fit everything into a smaller unit and still have room to access everything, then transfering to a smaller unit is a great idea. Maybe you initially got a big unit because you had more stuff, but you've gotten rid of a lot of it since then; if what you have left will easily fit in the smaller space, you may as well move it.

Again, your rent on the newer unit will still eventually go up. But in the meantime, especially if you're going to have the unit for only a few more months, you may as well save some money.