I think I must have been living under a stone for the last few years, but I only just found out about this. We use the crossing fairly regularly but certainly not every day/week. I thought the DART-tags were for people using the crossing daily! Turns out that you can apply for a DART-tag online and make a minimum initial payment of just £10 (I paid mine on debit card and didn't set up a direct debit). They will then send you the tag and each time you use the crossing it will debit £1.33 instead of the usual £2.00. You can apply online or by post. If you have an online account you can set alerts for when your account is down to £5 to remind you to top up. You can have multiple tags per account is other members of your family need one (will probably get one for my daughter who I always have to remind to get change for the tolls). For us, this is a really good deal and one I wasn't aware of even though the scheme has been running for a few years now. Hope this helps someone else who didn't know either!!