It is possible to contribute outside of payroll, however it is rarely a good idea since it is often more work for less tax savings. To explain, if you contribute money directly to the account by writing a check or sending cash instead of doing a payroll deduction:
- You will not save payroll taxes (nearly 7% percent savings).
- You will not see any income tax savings until you file your taxes (rather than immediately if you do a payroll deduction)
- You will have to go through the work of filling out a deposit form and correctly indicating the amount on their tax return
If you want money in an HSA to pay for medical expenses, it is usually much easier to simply pay for those expenses with the money they are planning to put in the HSA with the deposit form. Then you can do a payroll deduction and if you wish, reimburse yourself. This will mean they save payroll taxes, see the tax savings immediately and save the trouble of using a form.
Click here to see how to set up reimbursements: