Why the pricing basis matters more than the sticker price
Two AP tools can list similar headline prices and still cost very different amounts once a team grows. The number that predicts next year's bill is not the sticker price, it is the pricing basis: does the platform charge per user or per account? BILL's plan prices are per user, per month. Essentials runs $49, Team runs $65, and Corporate runs $89; every one of those figures is a per-seat rate, so adding an approver adds the full rate again. Nickel prices the opposite way. Nickel Plus is $35 / month, flat per account, not per user, and that single price includes Unlimited users.
The shape of the cost curve is easy to see without inventing a specific dollar total for your team. A five-person AP team on BILL Essentials pays five times $49, every month, and that multiple grows every time headcount does. The same five-person team on Nickel Plus still pays one flat $35 / month, whether it has five approvers or the full Unlimited users the plan allows. That gap between the two curves, not either plan's name, is the whole point of this comparison.
When flat pricing fits, and when it stops
Flat pricing fits when you expect to add approvers or AP staff over time and do not want the bill to track headcount. It also fits teams that want a predictable, board-reportable software line item. Nickel Core is free, $0 / month, with 3 active users included, so a small team can test the flat model before committing to Plus.
Per-user pricing stops being a problem when your AP team is small and stable: two or three people who are not going to grow. In that case BILL's deeper integration bench, QuickBooks, Sage Intacct, Oracle Netsuite, Microsoft Dynamics, Xero, Acumatica, may be worth paying per seat for. BILL is built for scaling one platform into a growing finance stack, not for holding a flat number on a lean team.
Where Melio fits in the shape
Melio sits between the two models. The free Go plan, $0 /free forever, covers one user at no cost. Once a team moves to Core, $25/mo, or Boost, $55/mo, each additional approver costs $10/mo per additional user. That is still a per-seat charge, unlike Nickel, but it is a much smaller per-seat increment than BILL's $49 entry rate. One exception is worth flagging: Melio's top tier, Unlimited, is $80/mo, unlimited users, which removes the per-user penalty the same way Nickel does, just at a higher flat floor and only once a team is already paying for the top plan. See the full per-seat cost breakdown before assuming Core is the ceiling.
When to reconsider flat pricing
Flat pricing is not free of a ceiling. Nickel's own flat-fee model tops out at Nickel Pro, $300 / month, built for higher transaction volume than Plus's $1M transaction limit allows. If your AP team's transaction volume would push you to Nickel Pro anyway, that is the point to actually run the comparison against a same-size BILL Corporate team instead of assuming flat automatically wins. A large, established AP department paying BILL Corporate's $89 rate per user gets deep ERP integrations, QuickBooks, Sage Intacct, Oracle Netsuite, Microsoft Dynamics, Xero, Acumatica, that a flat-fee platform is not built to match. The trigger to reconsider is not a specific headcount; it is whether you have already hit Nickel's top flat tier and are still choosing on price alone.
See the full pricing breakdowns for BILL and Nickel, or start from the AP automation buyer's guide if headcount growth is not the only factor you are weighing.