Yes, contributions into a Junior SIPP benefit from tax relief and this is one of the main advantages of a Junior SIPP. When you pay money into the SIPP, 20% tax relief applies. For example, if you pay in £100, a total of £125 goes into the account. Contributions are usually paid net of tax. So if you pay in £100, the Junior SIPP provider will then reclaim the 20% tax relief (£25) from HMRC and this will be paid into your account once received from HMRC, which can take a few weeks.