Assignee cost-of-living index lagging months behind the naira: what do you do in between?

We ask our provider for an off-cycle review when either the exchange rate or reported inflation moves more than 10% since the last update. Most providers offer this, sometimes for a fee. We have triggered it three times in two years for Nigeria and once for Ghana.

I would be careful about adjusting on receipts. Assignee spending patterns include a lot of imported goods priced in hard currency, and people naturally bring the worst examples. We instead pay a larger share of the package in home currency and let them convert as needed, which removed most complaints.