Most small businesses do work that requires them to buy things on behalf of their clients. This may include stock photography, website themes, and more.
If you need to do this for your freelance business, you should try to get reimbursed for the expenses.
Obviously, the first thing you should do is make it clear in your client agreement’s payment provisions that your client must reimburse you for expenses. You can make this it’s own dedicated section, or you can just include a sentence or two about it in the normal payment provisions (the more important the provision is to your specific deal, the more important it is to separate it out into its own provision).
When writing the provision, be sure to explain how you will invoice for the expenses and how/when the client must pay for those expenses. Sometimes you’ll need to invoice separately for them, while other times you can just include them in your normal invoice. You may also want to think about whether you can mark them up when billing your client. From there, establish a timeframe for when the client must pay the invoice. Net 30 is typical.
Most clients will be suspicious about reimbursable expenses. Thus, it is very common to include a provision that says the client is not required to make the reimbursement unless the client approved the expense up front. If your contract requires this kind of approval, then you should list as many expenses in the contract (or scope of work) as possible, but then make sure you get permission later for new expenses that arise.
Also be clear about how that consent will be provided. Oral? Email? Writing? Etc.
There’s so much more to learn! Here are a few related guides you should read: